I found something else that might be useful. A vehicle much larger than an explorer.

Site: https://www.renderosity.com/mod/bcs/vezdechod---the-land-cruiser/99297

The images are for sale, so I'm reluctant to post them here without permission.

Perhaps it could be a mobile planetary exploration base? I could see a group of three of these operating several kilometers apart on Volturnus... Rival groups from Streel, the PGC and Cassidine.

Players could be attached to one of these groups during the Mechanon Revolt and have to make their way back to Volkos.

Type: Mobile Planetary Survey Base

Manufacturers: Pan Galactic, Streel, Cassidine Development and others

Movement Type: Wheeled or Tracked

Alternative Movement: On planets with water, most MPSBs would be equipped with a supplemental water jet propulsion system to cross rivers, small lakes or inland seas, but they are not generally used for oceans. These vehicles are not submersibles, however.

Size: 60-75 meters long, 12-16 meters wide, 25-30 meters tall

Power: typically a chemical/fuel cell powerplant (similar to a Size A Chem Drive in Knight Hawks) supplimented by two large power generators along with 4 banks of six Type 4 parabatteries that are used for motion, lifesupport, and general functions. May have supplemental solar arrays for recharging batteries during daylight.

Range: about 4,000 kilometers at maximum power and a life support

Land Speed: Cruise: 15 kph, Top: 25 kph. Hey, these things aren't built for speed.

Water Speed (if applicable): Cruise: 10 kph, Top: 18 kph.

Crew Size: 12 to 16 with temporary accomodations for up to 24 survey crew members (8 foldout triple bunks in what is otherwise a common room/recreation room)

Life Support: These vehicles are generally watertight and can be sealed against hostile environments. Main life support will accommodate 13-20 beings. May or may not have a supplemental life support system.

Robotic support: 0-2 warbots; 0-4 combat and/or security; 0-1 robot brains; 2-4 heavy-duty robots for excavation, quarrying, etc.; 2-4 maintenance; 0-1 medical; 0-2 reconnaissance robots (Eleanor Moraes type); 0-2 repair/engineering; and 0-2 service robots. The number of robots depends on the type of mission and size of the vehicle. On a contested world, such as Laco, the mobile base typically would have a full compliment of warbots and combat/security robots.

Typical Sensors: Type G: Radar, 15-50 km range; Type F: Infrared, Radioactivity, Seismic, Sonar, Ultraviolet, Visual, VS Zoom Lens; Type D: Beam, Intense Light, Parabolic, Direct Micro; Type B: Shape and Odor.

Typical vehicles: 1 jetcopter or aircar (depending upon world); 2 Explorers (or 1 normal Explorer and 1 Heavy Explorer); 2-6 personal vehicles (glijets, land or hover bikes, etc.); 0-2 survey airships (Eleanor Moraes type). If need be, one of the explorers could be swapped out for a Manta mini-sub or Bathyxplorer.

Typical Levels:

Deck 0: Fly Bridge. At the very top of the Mobile Planetary Survey Base. This is typically an open-air level though models made for hostile environments will have this area enclosed. This is where the antennas and much of the sensing equipment is located. In the open-air configuration, there are four heavy weapon mounting points, two forward and one to either side. Accessed from stairs from Deck 1 A.

Deck 1 A:  Main Bridge, computer room, commander's ready room, navigation room, heavy weapons locker (if applicable). Accessed from exterior and interior stairs, 2 elevators (1 passenger, 1 service).

Deck 1 B: Air pad, for the jetcopter or aircar. This is located roughly mid-vehicle. Accessed from exterior ladders/stairs.

Deck 2 A: Recreation, sleeping quarters, common room (auxiliary bunkhouse). Accessed by stairs, ladders, and 2 elevators (1 passenger, 1 service)

Deck 2 B: Engineering Control (accessed from Deck 3 stairs/ladders, central engineering elevator, or exterior doors)

Deck 2 C: Rear Bridge (accessed from Deck 3, stairs/ladder and rear elevator)

Deck 3 A: Forward briefing room, offices, laboratories. Access: stairs/ladders (internal and external), 2 elevators.

Deck 3 B: 2 generators, chemical fuel storage. Access: central and rear engineering elevators, stairs, ladders.

Deck 4 A: Mess hall, forward observation lounge, additional sleeping quarters, medical, laboratories.

Deck 4 B: generators, chemical fuel storage, life support, parabattery banks.

Deck 5 (sometimes called 4-M): This is a half-level that is normally accessed by technicians and repair robots, it is where much of the plumbing, waste treatment, water/air recirculation and other lifesupport and HVAC systems are located.

Deck 6: Hanger Mezzanine. This is part of the vast hanger level and contains store rooms. On the exterior of the vehicle, more cargo boxes and fuel storage tanks may be mounted. There are vast doors, one forward and one aft, with large cargo elevators/ramps capable of lifing vehicles from the ground to the hanger level.

Deck 7: Vehicle and robot storage, vehicle and robotic repair equipment; crawlspace access to the "drive cars" -- where the external wheels or treads and their electrical motors are located. 

Deployment: Typically the Moble Planetary Survey Base is built at an industrial world, loaded onto a system ship/lander, which is then towed to the appropriate star system by a Void jump-capable tug.

Cost: Big Credit-Os

Use: a MPSB is part exploration vessel, part home base/resupply and repair shop, part laboratory, and part light manufacturing facility. The megacorporations will deploy these mobile bases in groups of three that may be 1-2 days apart from each other via ground or jetcopter flight. In addition to its own crew, it may service 0-8 other exploration teams that may be equipped with Explorers, Heavy Explorers or ARCs (see Frontier Explorer magazine), that are conducting their own scouting missions.

Most MPSBs have 4 coats of spray armor already applied to their exteriors. They typically do not mount weapons though exterior mounts are usually already in set locations that can accept man-portable heavy weapons (the typical heavy laser, sonic devastator, rocket launcher, etc.).

They have 2 powerful spotlights mounted on towers, one to either side of the front of the vehicle, that can cover a 270-degree arc (both cover the forward hemisphere while the left light can cover the leftside of the vehicle and the right light the right side). Plus there are supplemental external lights.

If needed, two medium turrets can be mounted to the MPSB to carry vehicle heavy weapons, though this will reduce its cargo/laboratory/passenger carrying capabilities. Usually that's why warbots maybe assigned to help escort the vehicle backed up by armed vehicles.

 

That would make sense.

Here's something from conceptvehicles.blogspot.com that could represent a Mobile Planetary Survey Base.

I don't think it's for sale. I would credit the artist, though I can't seem to find who did it. I just did a search for a "planetary exploration vehicle" and this was one of the things that popped up.

Another one is here:

Credit goes to: Adam Burn, Tuesday, June 25, 2013