I'll keep this as simple as possible and tell you what *I* would do ( and did) with a Prosine 2.0 IC. It's called a whole-house setup, which means it's simply another AC source for your entire coach.
First, your WFCO should be disabled, as should your transfer switch (maybe..see below). The Magnum can take care of everything, including being a surge supressor/power police unit. My Pro had all that functionality too, so I assume yours does. (No, I haven't read the owner's manual) If that's a fact, you want the M to police all your incoming shore power. With a subpanel you won't get that, plus it's a lot of work. I don't see what kind of generator you have in your profile, so I'll assume it's outboard (portable). The wording you used leads me to think it may be built-in, so perhaps you'll correct me. If so, then the xfer switch comes before the M AC input.
Put the incoming AC from shore to the M, and the outgoing to your AC panel. That's it, you're done.
This way, you get protection from bad shore, you get hybrid support if your generator can't handle it, and, your whole coach runs on it.
"If I'm wearing long pants, I'm too far north" - 2oldman
