Onboard LP gas generator?

I have an Onan 2.5 in my TC. I wouldn't have ordered it that way but I bought used and it had one. I use it for the microwave, coffee maker, toaster, etc. It's very handy: starts right up, nothing to get our or put away, and no need to mess with gasoline.
I don't know how much fuel it uses but I've never run out with 2 20# tanks. I can't imagine running it non-stop for the AC. If I'm camping when it's hot I go somewhere with electric. I like to camp out in the middle of nowhere but I generally do that when it's cooler.
I have run my gen. for 6 hours at a time powering my house during a utility outage. It started on a less than full tank and never switched to the other one.

I have the onan 2500watt LPG. It is great as a convenience, to be able to hit a switch and start the sucker up and do what u have to do and then kill it is very nice. I agree that it is loud, my dad had a 2000watt honda the thing was like 1/2 the noise even at full load and u could put it in the bushes or build a bit of a wall around it to diminish the noise even further. For constant usage for an AC unit i would say it would drive me nuts but that just my opinion. In terms of LPG usage i would say its quite low as in i dont notice significant reduction in propane during my limited use (few hours). I really have only used mine at the most for a couple hours at a time for battery charging in winter. We never run the thing if someone is camping near us, only if we are camping somewhere by ourselves.

Information can be found here for the fuel consumption: Onan 2500watt owners manual PDF

According to ONAN it uses

1.2 lbs/hr under no load
1.6 lbs/hr under half load
2.3 lbs/hr under full load

I have an inboard LP generator 2500. I love it to make coffee, espresso, air drying, recharge batteries, especially if I use the furnace in cold wheather and recharche the computors when boonducking.
For AC, this is another story. Mine will run the AC when it is not too hot! When it is hot, like around 95 and up, the AC needs too much power for restart and the gene stop working. I guess I would need something like 3000 watt.

As for how much propane, I never calculated but the gene is running full blast when the AC is on, so I presume it will suck up the propane pretty quick.

I love having the built in LP Generator available at the push of a button. It is on the loud side though. Running it day and night for A/C would be annoyingly loud for us.

I do have a Honda 2000 Generator that we use quite a bit for camping. It is quiet enough that when in camp for the night we just let it run until we crash into bed.

Note that we never need A/C boondocking in Oregon :)

If I was in the deep south I likely step up to a larger Honda that was strong enough to run the A/C, and keep the built in LP for the push button ease.

I have a onboard 3400wt and I hardly use it I am getting ready to sell it and get a gas portable. the onboard is loud and vibrates the camper to much I thought I would like it but I don't.

Hello,
I have a 2001 S and S 9.5 non slide 4 season camper with two 20lb propane tanks onboard and an Onan 4k lp generator. We have camped in 90 plus temps and as far down as 15 degrees. The lp is used for our fridge, cooking and heating and cooling. We normally have the AC at 75 and the heat at 60 degrees. Very comfortable for us! We can sustain our camping experience for almost two weeks!
If we simply boondock for a cold weekend (mid Friday to late Sunday), we use about a quarter of our 20lb tank.

We are very happy with our generator at this point. It runs like a charm.

Of course any use will depend on size of camper and personal comfort.

Good luck with whatever you decide on!