Some good advice above. Some bad advice. A lot of irrelevant advice.
Assumption 1: Everything in your 5th works the way you want it when plugged into a 50 amp 240 volt RV outlet.
Assumption 2: Your 5th has a good inverter/charger and can run everything you need including the refer.
Info from your post: You want to run a refrig 24/7 to keep food frozen or cold.
Needed information: Is this a storage location or are you intending to live full time in the 5th? I think you suggest you want to live in it full time or for long periods.
If it is a storage location and you want to just keep the refer cold, a generator is going to be a special problem. A small generator running 4 hours a day and 14 hours once per week would work with a modest battery bank to do the job.
This of course requires frequent visits add fuel and start and stop the generator. A better solution is grid power because it works reliably without frequent attendance and does not require periodic maintenance.
If you are going to live long term in the 5th and you are frugal with power consumption, the same small generator and battery bank would work. I assume you will be there everyday to manage the generator.
If you want everything to work including the air conditioners, you will need a much bigger generator and will need to run it full time or nearly full time. (50 amps at 240 volts = 4000 watt generator.) Most portable generators are not up to the full time running gig. Many whole home standby generators are also not up to full time year round running. So you would need a 4000 watt gen that is rated to run full time for long periods. Generally these are not available at big box and hardware stores.
Again, grid power provides uncomplicated reliable power. In the long run, grid power is the best solution for full time year round power.
Don't worry about the issue of damaging electronics with the wrong kind of generator. That issue has to do with battery powered inverters. Some battery powered inverters are not good for electronics.
I wish you good luck and happy trails ahead.