what is the cooking load "watts" of the crock pot
what is the 'load' listed on the compressor of your little freezer
come back with that info and we can be more precise
with out that info
my recommendation is a Tripplite PV1250FC
1250w continuous, 1875w for one hour, 2500w peak for 10 seconds
it is made to run motors aka tools/compressors
i used one to run a residential fridge for 7yrs full timing off grid
about $300
weighs 22 pounds, it has big copper transformer in it
which is why it works so well for powering motors
and it has a load sense that can be adjusted