Socksshep Yes it is entirely possible.In fact I did a 7 day tour with three others all of whom rode mtn bikes two with rear racks and panniers the third had rear rack and panniers plus a bob trailer.The third ,forum member Dwagenheim,subsequently went on to ride that setup from Alaska to Panama .Check his journal above in the travelogue section for details of his mtn bike touring.By the way we averaged about 75 miles/day and I think most onroad mtn bike tourers use some kind of slick tires rather than knobbies and add some kind of bar ends to add handlebar position variety.One on our tour used an aero bar which he liked as well.