1) Electrical Management System for sure! For power surge, low voltage, and faulty ground protection - especially while operating the air conditioner.
2) LED light bulbs - for both the energy (battery) conservation AND the extended bulb life. I burned out four of the OEM incandescent bulbs in the first 2 months of full timing. I replaced those (and about 1/3 of the others) with LED's I found at Menard's. Haven't had to replace one of them yet. Plan on changing out the rest as the budget allows. Glad Jayco has gone with these as standard, now.
My generator has also come in handy when the power went out at two different campgrounds. And I love the solar-powered LED light strip I added under my awning! Of coarse, the roll-out trays I built for my pantry, and the "nesting racks" for my dishes are great mods, as well. Next mod is a PSW inverter, so I can run my C-PAP machine off my battery. Would get much better sleep when stopped at a rest area. Then a pair of true
deep-cycle batteries, so I can make it through the night on just
the batteries. Rustic camping, her I come!
After that, covers for the ceiling vents, a digital thermostat . . . do we ever stop adding mods?