Do you have the formulas for sizing the battery banks?
You better have some 20-ply tires on it to haul all that lead!
Charles Marine, Xantrex, Statpower - all good brands.
A 3000 watt load at 13 volts is 250 amps, then you figure the efficiency at 95% and you get 263 amps.
"all day" would be what, 10 hours?
That's 2,630 Amp-hrs.
One group 31 battery is 90 Amp-hrs.
You'd need 30 group 31 batteries...
Are you SURE you hate generators?
They make sound boxes for RV generators, and better mufflers, too.
for the record, I kinda LIKE generators...