A high quality silicone based caulk would work fine on the doors and windows. Ray, IN is correct to the point of low quality (cheap) caulks don't work on RVs. Anytime you apply caulk, clean the area first with some sort of adhesive remover to remove any grease or wax that is remaining. Even after using the butyl behind the window, door, etc, a good caulk job will go a long way of keeping the butyl from decomposing. When I reseal a customer's unit (as well as my own) I take my time and make sure the area is prepped properly.
Good luck on your purchase and enjoy your RV.
01 250 PSD Lariat; Off Road; SB; Green; Beige Leather; Black Tube Steps; Tonneu Cover;
Reverse sensors; K&N Air Filter; ;Banks Six-Gun Tuner and Monster Exhaust; A-Pilar gauges; Rancho RS9000X; truckputer beta installed; Marinco plug upgrade; Towing