I have already considered padding the seat side of the rack for back/side cushion for riders as the rack can bump and bang you around if terrain gets rough.
I like the rear load for couple reasons:
1 - keeps the dogs off my seat and from tearing it up with their claws
2 - the dogs want to be as close to the front as possible, so it makes a nice barrier to keep them from trying to get in my lap
As far as passengers go, an adult can ride on the back of the rack and it's not too heavy or off balance for the four wheeler.
I will let my buddy drive sometimes and i'll ride with the bulldog on the back rack, actually not a bad ride. And my younger sons likes riding on the rack lol, guess it's that 'riding in the back of the truck' concept.
Maver!ck