Most all of the wires, I believe, are for the gauges. If you don't want the gauge, you don't need the wire.
If there is an on/off switch, you probably want that switch to be somewhere, but doesn't necessarily need to be on a "control panel".
When I pulled the inner skins off mine, I took a look at all of the wires and was like.. Oh, no. But it turned out to be a lot simpler than it looked. If you look at the 12v
distribution panel, mine has 4 wires coming out. All 12v
junk runs off of one of those 4 wires (or the blue from the tow vehicle).
The 110 has 3 wires. One for the AC and one each for 1/2 of the outlets.
On mine I plan to put the water pump on/off switch somewhere and def. an ammeter somewhere. Not sure that I care about water level gauges or the rest of that junk.
Don't know what gauges you might want for a solar charging system.