A huge number of RV dealers get their parts from Coast, which offers their line in the Go-RV
website. Specify any U.S. dealer, and you will see US$ prices. While it is used by many dealers to show what they have available for retail customers in their stores, direct ordering for shipment is also offered - I have no idea what shipping to remote locations costs, as I have only purchased their stuff in person at local dealers. It is easier to use their catalog on paper, but the entire thing is available on the web site.
They have a wide selection of those utility (or "service") covers, for power, water, etc.