Here are photos of my prototype "solar generator" box. It is designed to use either external 120v power or solar. Since I took these shots I strengthened the holding board, added in external 120v outlets, put in an electronic power sensor in both the 12 and 120 v sides, this automatically disconnects the solar panel and inverter when shore power is connected. The panel is a 50w with 25' of cable with quick disconnects and can be easily extended if need. I've also added a simple tilt frame to the panel so it can stand on it's own.
This is the unit closed

This is the "guts" of the unit. I've since made the plywood backing panel better, cleaned up the wiring, added in the external 120v outlets. The charger is one I had laying around. 2000 watt inverter, solar controller.

That is a little, freebie HF volt meter, works fine for this

Brushless computer fans are used to pull air out of the box to reduce heat and the potential of gas build up. The switches (now labled) control the various devices. I've also added automatic disconnect circuits

It works great, I use a little folding dolly to move it around. I can set up the box at the campsite and then put the panel in the sun. This stuff will now all go into the trailer.