I remember Brian from FR once saying that FR lists what the lpg tanks actual usable lpg is.
I have to look it up but I think my 2016 2801 Forester is like 9.8 gallons or thereabouts. That equals about a 43 pound lpg tank. The 2016 MBS is also listed as 9.8 gallons.
If yours is 16.6 gallons that is equivalent to about 72 pounds of propane. That seems like quite a bit for an mbs but if your generator is lpg I would assume it's possible.