Just use the carpet shampooers that you can rent and do it the same way as your house. Be careful not to use too much water in any one location and suck out all of the waste water that you can. Make sure that he uses whatever he has to insure that the carpet dries as quickly as possible. This may mean running the AC or heater a little longer than usual, or opening the coach up in a low humidity area so that it dries quickly and completely.