FYI, you don't actually have to put the sticker on the vehicle, you just need to be able to display it. In Texas Traffic Code terms that means show it to an officer upon request, so you can carry it with your other paperwork (ins., etc.).
In Texas you can register any former military vehicle from any nation, regardless of vehicle size, weight or year. This includes trailers. This is in 504.502 ss (i).
Carrying copies of the appropriate codes is a good idea, since most officers have no idea it exists for military vehicles. Sec 504.502 covers "Certain Exhibition Vehicles", with ss (F) being the part that says you can use bumper numbers. Section 548.052 ss(5) deals with the vehicle being exempt from safety inspection.
If you see any information that refers to Sec 502.275, that was repealed and replaced by 504.502 in 2003.
Cheers