I personally would put the 3 on my tow rig, allowing the golf cart weight to be centered in the garage....otherwise your cart would be heavy to one side?.. not the best on your trailer suspension and tires, etc.
I sit here like the RCA dog as I read this. The Op stated he has a 5th wheel, and Im really interested in seeing how you put the 3 "ON" your tow rig.
Meanwhile, if weight is an issue, put 2 on 1 side, golf cart in center, and other yak on other side. Personally, I load my golf cart on driver side for the last 8 yrs and Im planning on configuring to carry 2 x 10' yaks as well. Probably a carpet wrapped board between them and ratcheted to the floor.
I did find this external option. It would require adding a hitch....
https://www.youtube.com/watch?v=4WxQJPyfUGU