https://motorsnorkel.com/propane-consumption-rate/
Here is some info on generator running time on propane.
Edit: looks like 1000 watts for 1 hour requires 20,000 Btu which is roughly 0.9 lb of propane.
So for my minimalist “just heat and net, ma’am” application, which I figure will require less than 1000 watts average, a 20 lb tank can potentially last most of a whole day. That assumes optimal generator choice - powering a 1000 watt load with a 14 kW genset is, I would guess, going to be far less efficient than with a 2 kW generator.
1 gal gasoline has 114,000 Btu, so a 5 gal can of gasoline can potentially last over a day, again assuming optimal genset choice. With multiple refuelings.