I've seen RV parks who had access to pet sitter services, but never considered it for my dogs. The Aussie and Cattle Dog were naturally going to defend THEIR property if we weren't there. Period. Eons ago, another Aussie wouldn't let my Dad into our house to drop off a tool - someone he knew and adored - but we weren't home. My Dad, very knowledgeable about dogs, said Casey was VERY serious about taking his arm off if he walked through the door - eeks! So even if dogs have been "introduced" to someone - when "Mom and Dad" aren't home, it's a whole new ball game.
Jimmy and Ben (half aussie/half poodle) are less defensive; and would be more inclined to run away from a stranger. That's not good, either.