I think it would be cool if the small flatbed trailer had selectable 4-lug and 5-lug wheels. I tried it, but when I loaded up the game with my modification of the small flatbed trailer, the pickup didn't load. If the devs did it, then it would work as they are pros at modifying vehicles
I agree with you, the trailer should have different wheel lug options, that way we could put all the kinds of wheels onto the trailer.