I bought a used 34' Chevy 5500 Kodiak Super C (Jayco Seneca) with the Duramax. It has an 8,000lb hitch. Carrying capacity is more than adequate for anything I need to take. I am pulling a Aerovault trailer, though you could easily pull a 20' trailer behind it. As I have told anyone that would listen, this is kinda the "unsolveable problem"(actually it is solvable, but my powerball numbers didn't pan out either.) Essentially, the advantage of the motorhome, especially a super-C is that you get a Diesel dually for not much more than a new diesel dually but it has a house on it. The RV is 34' long, whereas the big enough toy haulers or race trailers are VERY long making maneuverability and parking a huge pain. I can turn my fairly short wheel-base RV around in my subdivision. I have limited length to park so 34' is my limit.
The downside is that you don't have a run-about vehicle when you get there. For weekends it is no big deal. For Lincoln, we're probably gonna get a rental car.
Lastly, I am a big-fan of aero and lightweight as it helps with towing mileage.
Checkout ATC. They have a bathroom package for their V-nose trailer that doesn't take up much space. That gives you 50 fresh + 50/50 grey/black + toilet, sink, and shower. Put a couple of chairs in there to sit on and put an A/C on the top of a 20' trailer and you are at 3500lbs without gear. Get a duramax 2500 and tow at 75mph all day.