First off, welcome to iRV2!
Re: Fuses for the trailer plug. Most folks ask for the fuse location when there's a problem with one or more signals at the trailer hitch connector. The thing is, the answer to your question depends on which signal(s) have the problem- at least for a Ford-based Newmar model. So, could you briefly explain the problem you are trying to solve?
Also, you should add a "signature" to your profile. It contains whatever info you want; most people put info about their coach there, so they don't have to type it into each message. Instructions for adding a signature are here