With a residential fridge I would allow at least 1,000 watt to start the fridge (NOTES FOLLOW) and as noted if you want to nuke your lunch 2,000 for the rest.
Else the 1000 may be able to handle it or 1500 to be safe.
The note: There are a couple RV Fridges they are specifically designed for an RV fridge footprint and cut out. at least one Norcold and one Dometic, that are NOT absorption cooling (ELectric/Propane) but rather Compressor designes (Danfoss class compressors, NOTE; Do not know if they are actual danfoss since I don't have one) the do not need 120 volts,, Just 12, and only about 3-4 amps at 12 volts (.3 to .4 at 120) That's 36 to 50 watts folks.. Now if you want to go compressor. that's the way to do it in my book, They are expensive.. till you price modern residential fridges and then change your undies.
Finally batteries. MINIMIMUM 1 pair GC-2 per 1,000 watts.