Welcome to owning a motorhome. I guess you get to know your coach and get to know what is normal and what you can control over time. Doors, latches, racks, stuff you have addded, chasis, etc. You will never take the squeeks and rattles totally out, but you will learn where they are coming from and what you can do to lessen it.. Some tips above a good ones. Insulate hard surfaces from each other using towels, etc. Use sticky foam tape for some built in items that may bug you.
Just try and keep the noises you totally have control over from happening...like trees scraping across the top or scraping the tanks across an incline, etc...