Are you talking about super singles? If so, I have quite a bit of experience with them under my truck camper. I have come full circle from various 285/75R16 to 14.50/65R16's to 15.50/55R16's (375x65R16) and finally to 315/75R16 AT-3's. The question is how narrow a trail do you expect to travel? If just dirt roads with a width of say 15 feet or more, just keep running duals. Oh, and the wag about rocks getting stuck between the tires is very rare indeed and not something to worry about. I can't get my Photobucket to open right now but will try to post some pix later once I get home.
jefe