Interface Vehicles in DS & FT

I've got an idea I wanna try in Dirt Side (maybe with Full Thrust tied in?)
which is definitely not from Star Wars or Anime (so can I talk about it here?
<g>).

What I wanna do: Dirt Side game with the goal of a besieged force
needing to extract all of it's troops on Drop Ships/Assault Shuttles/
Whatever, before overwhelming opposition arrives on the table. (OK, so maybe
the beginning of ESB is similar, but I won't allow examples
of that most silly of futuristic combat - walkers.)

ANyway, the DirtSide rules recommend against, and don't seem to provide a way
of, designing largish vehicles such as the drop ships and shuttles. I don't
want to simply say they're impervious to ground fire, or have to make up some
other ad hoc rule. I'd rather try to assign appropriate capabilities and
costs.

Any suggestions? If they can ties in with chances to blow the transports apart
in aerospace combat, or space combat in Full Thrust, it's a plus.