Welcome to iRV2.
I'm not up to speed on Ford chassis and their ratings , but if the 22, means ; 22,000 LBS , GVWR ; then many manufacturers are now building on 24,000, even 26,000 LBS. GVWR chassis .
This number also relates to the CCC; ( Cargo Carrying Capacity ) of the RV.
Many motor homes leave the factory nearly overloaded so you have to get all the numbers , no sense having big compartments to carry all your gear if the chassis won't carry the weight.
Some of the chassis have a very low , TTC, ( Trailer Tow Capacity ) that can make finding a toad ( your tow behind vehicle ) next to impossible.
You need all the numbers to make an informed purchase.
JMHO: Salesmen will say anything to get you to buy the vehicle they have , so proceed with caution.