Just returned from a 3,000 mile round trip from Houston area to Richmond Virginia. Averaged 9-10 MPG pulling 40ft 5th at 17,000+ pounds.
IIRC I got around 12 MPG with the Bigfoot.
2018 RAM Cummins, Aisin, 3.73.
Pin weight of the 5th and Bigfoot weight is very close...4,000+.
edit add: Since you have already sold your trailer, I would wait a bit before I jumped back into any kind of RV. I'm thinking fuel prices are not going down anytime soon. Let's see what happens after November this year and 2024.