I was going to say you will not have enough tongue weight with motorcycles on it and you'll get ridiculous sway that could cause a serious accident. you would need to cut and add a deck. Even so you still need to figure out if you will have enough tongue weight without it being too much and out of balance. You'd probably be better off finding a camper with a deck on it, JMHO.
See you on the trail
Couple o' FJ40's, BJ70, PZJ77, UZJ100, TDI