"f11smith"......On that era coach, I would go right back to a 110V/propane refer. If you intend to do a lot of boondocking without running the generator EVERYDAY, you would need a lot of solar and associated components like chargers and batteries. 400-600 watts will not keep the coach afloat with an electric refer.
I would go back to a propane unit and use a moderate amount of solar if you need it for entertainment items. Your 400-600 watt of solar is going to require a new battery charger/inverter, more batteries and other small items to get the system to work. You are probably talking a couple thousand dollars, if you do it yourself. That's a lot of money to put into an older coach, not counting the cost of the new refer.
Buy a propane refer and add more batteries for boondocking. Batteries are cheap.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor