I meant to respond to this topic when you posted it, but important vacation chores got in the way. :B
I hinged my fridge vent several years ago, for the same reasons you did. I used two brass hinges, and installed a door holder above it.

I found some clip nuts and thumb screws from a server rack that fit the square holes perfectly. These were oddballs though, most server rack clip nuts are made for much thinner material than this plastic frame. I can’t remember what they were actually for.

Greg, I’ve also got an inverter in my camper that I can run the fridge from while traveling. The cord that the fridge is plugged into is running to the inside of the camper, and I can either plug it into the inverter, or an AC receptacle nearby. I just fished the cord under the fridge cabinet through a void that was there.
But, after installing a DC-DC charger in the camper about a year ago, I found that the DC mode on the fridge would actually work now because the camper battery voltage was being maintained at about 14 volts, which makes the DC heating element work much better.
So, now I have two ways to power the fridge from electric while driving now. I prefer to run it in DC mode, because the 25 amp DC-DC charger can supply more than enough current to run the fridge, and still keep the camper battery charged up. If I run the fridge in AC mode from the inverter, it’s pulling a few more amps than the charger can produce, and the camper battery slowly gets discharged.
:):)