[Espeefan]

I think the biggest problem would finding something to match the scale of the big rigs. Tamiya has some nice hardbody trucks that are 1/12 scale, but they are on the large size for the semi trucks, which are 1/14.5 scale. Actually quite a bit on the large side. It would be like comparing 1/10 scale to 1/8 scale. You'd be better off searching the toy RC sections of various stores, like you mentioned. Often times, their 1/12 scale trucks are on the smaller side. More like a 1/14 scale. The drivetrain would probably require you to look at the 1/16 scale RC rock crawlers, like the Losi and Venom trucks. Their axles are pretty nice for a scale model, just like you want. The problem with the Tamiya 1/12 scale trucks is that their axles are unrealistically wider then they should be, but it's all in sake of performance, just like the taller jacked up ride heights.

Another option for bodies to look for a toy truck, that is non-RC. They are around. Remember those Nylint brand metal trucks? Or even Tonka's? They are out there. Probably best found on E-Bay.