Your RV will consume more power than most 'guess'. The CO meter, propane leak detector and refrigerator together consume about 35 amp hours per day, or what a 120 watt solar panel will put back in a normal day.
I would recommend a pair of 140 watt solar panels, and a PWM controller. The MPPT are way overpriced for the couple of extra amps that they claim to put into the batteries.
This place has 12 volt nominal solar panels for $229 with aluminum frames.
SunElec.comYou can use 6" long 2" angle aluminum for brackets, with 3 holes 3/16" for #10 screws into the roof, and 5/16" hole for the 1/4" bolt into the panel framework.
Rubber roof sealant seals all the holes, and prevents leaks.
I ran #10 UV resistant grey wire down through the refrigerator vent to the controller, then to the battery.
Good luck,
Fred.