I'm not sure what the amp size has to do with running the fridge. A 50A converter will handle 50A. Doesn't mean you need 50A unless you need to power two AC's at the same time. As far as the fridge goes, if it's a standard Norcold, Dometic, etc then 15A is all that's needed. Even a residential fridge only needs 15A. Seems like all you need is an adapter to plug into your house. My res fridge only requires 4.2A. Don't know what my 5er fridge (Norcold) requires but I run it on a 15A receptacle. Also run my 13,500BTU AC on the same 15A receptacle when the fridge is running.