I have Kenmore 115V AC room air-conditioner, which
consumes 49W [39 in Power Saver mode] per my Kill-
A-Watt meter. The 4.5" muffin fan I sometimes use
with or w/o air cond. consumes 21 W.

It would be difficult to mount in a camper, but I
did run it on a 12V 12AH gel cell, charged by 2 of
my solar panels. It worked equally well on a 400W
MSW inverter, & a larger 800W unit. On the 400W
inverter, I turned the AC off/on/off/on, & saw only
0.1V drop at 12V DC [VOM, not 'scope], when using
a 40 Farad cap to handle surges. I am sure one of
my 1 F caps would be sufficient.

I don't recall the BTU rating, but it keeps my small
bedroom comfortable. My 5-room house is [under] wired
for 60A 230V service, with electric stove, dryer,
& water heater. I would not own a 30 A air-cond.