I agree with Ron that grounding issues are the cause of many 12v gremlins. I'll also throw out that sometimes oxidation can build up on the fuse blades and their contact points with the holders. It'd be worth changing your 12v fuses, or at least pulling out and putting back the current ones like 3 times to scrape them and refresh the contacts. That's worked for me before.
Lastly, you can contact Gulf Stream to get diagrams. It might be a chore, but if you really want them, give it a try.
2005 22' BT Cruiser 5211, Chevrolet 3500 chassis w/6.0L Vortec V-8; 6'x12' Cargo Trailer; Honda CB500X motorcycle for street and ADV riding; Yamaha TW200 motorcycle for dual-sport and trail riding...All of it for fun and adventure!