For flatbed trailer, this works. It's somewhat modular, so the things that get in the way of it being a standard flatbed can be removed:
http://www.toysrus.com/product/index.js ... Id=3045233 I have one with a couple of Armadillos and a squad of Joes all over it.
Vehicles I'd like:
1) 1:18th train. I definitely agree on this and would love one to set up around the original HQ or a Terrordrome. They make some decent G Gauge stuff that would work, but it's not a common scale, so hard to find.
2) carrier/launch capable rocket such as Soyuz, Falcon, Minotaur, etc.
3) Exo-Squad mechs (yeah, this might be stretching your original premise, but I want them). The mechs we've seen so far have been okay, but I'd really like the various Exo-Squad suits made to fit 1:18 scale instead of the sub1:24 they were originally.
4) This thing:
http://www.yojoe.com/archive/unproduced/vortex.shtml Yeah, not realistic and kind of goofy, but I still like it and want it.
5) Not sure, I guess just some generic everyday vehicles (Ertl has this kind of covered, but still a lot of things that could be made)