I had an HR long time ago. Had my electrician wire out of the transfer switch a 50A service female out let. the transfer switch "typically" has four outlets. One for shore power, one for generator and one feeds the house. the transfer switch automatically switches between the feeds. generator, typically takes the first choice. the forth outlet, generally is open. and thats the one which feeds OUT. could supply from shore power or gen.
I had a pole barn for the MH, had a 50A service wired out of the break out box in the barn. used to have power outage that could last a few days. in that case, I'd shut off the main for the house, wire the outlet to the house and run the gen set to feed the house. I also had an exhaust pipe thru the garage door for the gen exhaust. One march with an ice storm, we were out for 5-6 days, the gen ran the house, frideges, and heat, tv etc. obviously, YOU have to be aware of the loading for the specific gen you are running.
with the newmar(s), I had the trailer outlet service, except I had mine uped to 50A. actually, with my first newmar, they did not offer the trailer service. I had them add it as a custom option. the newmar setup has the advantage of being wired thru their break out box, which can provide some protection for overloading.