Shurflow, Aquajet and Flojet all make variable speed RV water pumps. I have no experience with these pumps but I speculate they will operate much quieter. Especially if run at a restricted low volume of water. Use a foam pad to mount and use flexible lines placed so they do not rattle against anything.
http://www.campingworld.com/maintain-your-rv/fresh-water/fresh-water-pumps-accessoriesSearch for some reviews on these items.
A low pressure circulating pump may also provide freeze protection of your pipes. IIRC you camp with minimal use of the furnace so pipe freeze protection is also important.
