I can't speak directly to Flagstaff but when I had my Fleetwood/Coleman the weight limit was 1100 lbs. I have looked at the Flagstaff's and they are very similar to the Fleetwood's. That was 2 king size beds.
Retired Fire Dept Battalion Chief
2016 Ever-Lite 232RBS
2012 F150 FX4 W/Max tow & Ecoboost (Best tv ever)
2018 F250 Lariat (ok but I miss my F150)
Getting old ain't for wimps!!!