I don't expect any of the characters' vehicles to survive the Case White landing, but if they do, or if they get new vehicles (definitely an intended action over the course of the campaign), they'll need to maintain them, likely without the benefit of a 'Mech Bay. Let's take Henry's Hawk Moth as our example for a moment, because it is the simplest vehicle to deal with.
The Hawk Moth is a light vehicle. It requires 30 minutes of maintenance per day to keep it up and running. Under the maintenance rules, each maintenance window involves 5 armor location rolls, 5 internal location roles, and a roll for the Light Gauss Rifle and another roll for its ammunition component, making twelve rolls all told. The internal structure rolls are fairly easy -- they have a Tech Rating of B, and I'm presuming all the ComStar-provided gear has a quality rating of E. Bert's character would likely be leading the maintenance teams with +4 in Technician/Mechanics, meaning that those rolls would be at a base target number of only 4. With the Tech Rating modifier (-2) and the Quality modifier (-1), that's rolling for a 1 on 2D6. Ah, but we've forgotten the penalties.
The team doesn't have so much as a Mobile Field Base, so they're looking at +2 right there. There are only five of them, so unless they can find some NPC AsTech's, they're looking at another +1 for Team Casualties. Finally, they get a -1 because we're using the Advanced Rules, putting their target number at 3. 3 on 2D6 is pretty easy -- that's be considered a sure thing in most circles. Indeed, on Quality E equipment, they need to fail by 3 to actually damage the internal structure. So the metal frame of the Hawk Moth is pretty safe. The engine has the same roll -- practically unbreakable.
The armor is only marginally more difficult -- its Tech Rating is one higher, but that's only worth a modifier of 0 rather than -2. The team needs to roll a 2 on 2D6 to damage it. Still not a huge concern -- that translates to losing a bit less than five armor points a month -- that can be repaired if they can get a supply of armor.
Now, the hard bits. The Light Gauss Rifle all that engine and armor is intended to maneuver and protect. TechManual p341 tells me Light Gauss Rifles have a Tech Rating of E (+2). The Quality Rating still applies (-1) as well as Field Repair (+2), Team Casualties (+1) and the Advance Maintenance Bonus (-1). Overall, +3, not terrible. But there's another issue. We're not rolling Technician/Mechanic anymore. This is Technician/Weapons, which Bert's character doesn't even have. We pass the baton to Morgan's character, who only has Technician/Weapons at +1, yielding a base TN of 7. Adding it all up, the Light Gauss Rifle needs a roll of 10 on 2D6 to keep it from becoming damaged. Every day. Statistics suggest it will be entirely destroyed within a month, possibly as little as a week. The ammunition bin doesn't have a Tech Rating, which is handled as giving it the unit's Tech Rating, which is E because of the Light Gauss Rifle. It won't last long, either.
The problem is exacerbated with the 'Mechs, especially Bert's ClanTech Black Hawk (ISRN Nova.) Anything with a Tech Rating of C or lower that's mechanical is easy -- car, trucks, etc. Maintaining weapons, especially 'Mech-grade weapons, will be virtually impossible. The party lacks the Technician/Nuclear skill entirely, meaning that maintaining anything with a fusion plant will be neigh-impossible -- their 'Mechs will be junk in weeks after they lose their connection with their ComStar support chain.
Cameron's character took Interest/Do-It-Yourself as a kind of catch-all skill I might let him leverage to help with the daily maintenance of things, as the gaps are large enough that either something is very easy to fix, or it is destroyed in a month. Otherwise, I believe the party will have their hands quite full just trying to keep their equipment together.
From a GMing perspective, this gives me obvious adventure hooks -- any high-tech requirements they have, like the Hawk Moth's Light Gauss Rifle, need to be obtained, installed, and used in short order -- they cannot maintain a standing ready-action vehicle force under the restrictions they'll have. This provides much more the flavor I was hoping for with this campaign. I just need to make sure I don't frustrate my players with the degradation of their toys, or push them into something rash before they're ready.