We know this is never going to happen. That is why it is in Pimp Dreams (where I think all ideas go to die lol)
I haven't even thought ahead of what the downsides would be. I just think of some positives.
For instance you have players who love to loot but not so much build and some who like to build but not so much loot.
A mobile truck base would allow the looters to not have to be a gazillion miles (km) from the base (even though yes some like the idea of that too. Many different types of playstyles in this game) giving them a little more looting time.
It also allows the base builders a little bit of freedom to not have to travel a gazillion miles (km) to do a little looting themselves helping with the magazine problem of the looters having to be the only ones feeding them magazines. Plus they wouldn't have to wait for looters to come back with materials. They could always have something to do.
Loot respawn rates could be turned up so you would have to make the rounds of most if not all of the populated areas before you could reloot a town or city so travelling would be a must.
As I mentioned though I am only thinking of some pluses of a mobile base. Am sure there are downsides too.
I also think the idea of a little convoy of trucks would be awesome lol.
Trucks with different benches, trucks with farm plots, trucks with dew collectors, etc
Once bandits are in then having to defend them from roving ones would be fun too I would imagine.
Anyway just my weird thoughts on the subject.