A 10 foot garage is too small if your trying to get sport utility quads in. First if you spin them sideways you block the door to the living area if that is an issue for you I don't know. The second issue would be is when you get the first one in your going to be spinning the second one on the beaver tail section of the trailer which isn't easy. I use an ATV jack to spin my 850 sideways and yes, it is not easy, even with my son helping. If you get a wide body trailer (102") you may be able to get them side by side depending on how they are equipped. Most utility quads stock are around 48" wide so you could get them in as long as the walls in the garage are clear of fold down beds etc...
Finally, have you considered an open floor plan? That would solve your loading issue and probably work much better when camping without the toys.