There seems to be a misunderstanding about Cab Fresh. My carton says nothing about repelling mice, just that it neutralizes / eliminates mouse-related odors. The critters built a nest right next to a packet of it in my rig.
Irish Spring soap is a favorite of mice around here, they ate 1-1/2 bars of it before we discovered them. Found chunks of it in their nests.
Dryer sheets really do work for removing bugs, but mice use them for nesting material.
If you have no mice in your RV, then quite simply, there is no way for them to get in.
Only thing I found to work is a snap trap under each wheel, checked daily. They get into the rig by climbing up the wheel initially, so I get them before they get that far. So far 100% success with this method.