What's your SxS? Is it a small RZR or a larger CanAm? I think either one would be too heavy to perch the front end on your moho's bumper. I'm no physicist, but the downward force of the SxS's front end and the rearward force of towing its rear end would pull your bumper apart.
Why don't you want a trailer? Plenty of friends in our camps have cargo trailers for their RZRs and CanAms and they're very happy with their setups. We love our setup too, but it's not for everyone (44' fifth-wheel toy hauler). We sure love our garage model though since it gives us so much living area and hauling room for the CanAm while we're driving and a nice big bedroom/mud-room once we get to camp.
I don't have a good suggestion for you besides a cargo trailer. All I know is that I've camped with literally 100s of OHV families and seen just about every setup imaginable, but never one like you describe. I have to think that if it were a viable option I would have seen someone with it by now.