I can’t see one RV filling all those needs. But two might.
I’ll take exception to the ugly ten year old coach statement. Late 90s Prevost, Newell and Foretravels are still good looking and many say, better than a new POS.
Look at motorhomesoftexas.com. Maybe a no slide Newell or Foretravel with lots of solar and tow a diesel Mercedes conversion. Leave the big RV on BLM or Fed land and take smaller sojourns in the little van. You could even add a towable Jeep or SUV into the mix and tow it behind either one, depending on where and what you were doing.
The Mercedes would work in Europe too as it’s supported pretty much worldwide.
Can’t help with the boats but it seems you do one or the other. I’d sell the boats.