This sounds like a 'what-if' project which is cool. So, my suggestion would be to purchase a second MENG Toyota kit and make a trailer/quad platform from the bed of the second kit. I've seen trailers like this in 1/1.
If this is not obtainable for you, then use your existing kit bed to get measurements from, and scratch build a flatbed trailer. For wheels, use the front wheels from a Tamiya or Academy Ford Mutt kit
hope that helped