The original Dometic in our 1999 Safari 27 died during a recent 2 week trip.
After researching options, we decided on an ac/doc unit. The hardest part was getting to dead one out. I'm not an electrician nor handyman. At any rate, I did what you are doing now and asked for help in the forums. In our '99, there were 2 wires that went to the old fridge 12V
control panel. And there is a 2 outlet standard receptacle wall mounted. I did get a professional opinion/look see from a marine mechanic. Most of the time the Isotherm will run on the 110. However, he said the wire gauge for the 12V
was more than enough to handle the less than 5 amp draw of the fridge when it runs on 12V. We had a carpenter do the interior finish mount. Everything works great. Looks great. And the whole install cost me my time and $140. for the carpenter. Some day maybe I'll redo the wire, but it now is way down the list. Sorry this got long. Hope it helps. Good luck.