Carrying a dirt bike on the hitch of bumer pull TT?

I am in the same situation. getting ready to buy my first setup and i want a toy hauler but I need something to tow the jetskis also. So i am thinking Id have to go 5th wheel for I see alot of them are designed to tow. I did find out some neat information about towing two trailers. Some states its legal some its not. So how does that work when going through other states?, I dont know. But in kansas its legal if your withing the weights. Also last vehicle must have brake assist on the axle.