I have several mods I've done to my travel trailer, including adding a support bracket system to the underside, and a future plan to add an inverter (I have a 1KW model).
Underfloor support:
It's comprised of 6" angle brackets, some Unistrut bars and a 24" wide by 1/8" thick aluminum sheet.
Here is the before assembly picture. It's upside down, and the bars haven't been cut yet.
And now it's installed:
Now the electrical part is pretty cool: I'm making a fully automatic transfer system between shore power and inverter power. It even shuts off high-current circuits like the converter, air conditioner, water heater and auxiliary battery charger circuits.
another mod I'm doing is adding extra circuits (battery charger and converter). Right now, the converter is on the same circuit as the "general" circuit.