Hi,
The freezer may kill this idea. Duty cycle, start up surge and running watts need to be known.
I have successfully run a crock pot which draws 300 watts, while trundling down the road. That represents a load of 30 amps @ 12 volts to the battery bank.
There are 12 volt crock pots--quite small but a much lower load.
Since your ride is a motorhome you may want to consider running the inverter from the chassis battery rather than the house. But make sure the alternator is able to support that sort of "extra" demand.