Would this one work?

I kept my outside vent for a reason. The hatch you've indicated would probably work but IMO, unnecessary and unduly expensive. Simply keep the vent you have. I used Gorilla Tape to seal off the "vents" and kept the vent to be able to change the water filter from the outside. It also allows me to inspect the rear of the fridge if necessary. I bolted the fridge in place once I installed it and I do check the tightness of those bolts during my annual rig checkup....Dennis

I sealed up my existing vent using expanding foam for the entire job. I sealed the opening and foamed it up from the back side. I do have some alum in the way so as it began to harden I closed the door and let the foam form around these parts. I did this mainly due to the fact that I do Winter camp in the cold and the ice maker water line runs down the back of the fridge in this open space. I came to this realization while spending Christmas in Flagstaff, AZ (-4 degrees). Glad that water line has a separate shut-off.
I spent last Winter in Detroit and it was rarely above freezing on a good day. -25 one day. With the heat generated by the fridge pumped into the back and allowed to vent through the roof, everything stayed in perfect working order.

TNGW1500SE wrote:
I vented the new fridge on the inside. There's a vent above it and one below it. I don't want to leave it open to the outside due to the bugs and critters. There's no screen on the old lower vent and the roof vent has a large mesh screen. I'm going to great stuff foam in the top vent.

Easy fix.

Cut a piece of FOAM insulation to the size of the lower vent, GLUE the foam to the inside of the vent panel. If vent panel is a sloppy fit to the trailer side add some weather stripping to the lower vent so it fits snugly to the trailer side frame.

Upper vent, cut the same foam to the size of the top vent, you want that to fit snuggly inside the vent, caulk around it and you are done.

I vented the new fridge on the inside. There's a vent above it and one below it. I don't want to leave it open to the outside due to the bugs and critters. There's no screen on the old lower vent and the roof vent has a large mesh screen. I'm going to great stuff foam in the top vent.

I recently installed a home refer too (bottom coils) and instead of sealing the vent I built a baffle that directs the hot air out the vent. I taped over the louvers in the rest of the vent to stop outside air from coming in. Have not decided what I'll do in the winter in WPB as most days are more like summer than winter.
OP, I would tape over the louvers in the vent for now and see how it goes assuming bottom coils. If on the back I'd leave it open like DrewE suggested.

If the fridges condenser coils are on the back, why not leave the vent (or at least some of it) intact to allow the heat from the coils to be dissipated outside the RV? Remember that the fridge is nothing more than a heat pump, moving heat from its inside to the outside; it seems to me you'd ideally like that heat not in the RV, at least during the summer. (It also would be more efficient if there wasn't too much heat buildup around the condenser coils.)

Why not just Glue a piece Styrofoam to the existing Door/Vent! Fill any leaks with Mono Foam!

If I was replacing Mine I would be insulating the whole RV wall behind the Fridge ,before installing any residential style fridge with Aluminum covered Foam Board and Mono Foam . The Original Vent cover can just stay in Place in case an RV Fridge is installed by a future owner!

TNGW1500SE wrote:

Bill.Satellite wrote:
That depends upon what style door you have now. The unit shows:
Cutout measures: 20-7/16" x 10-3/4" x 1"
If that will fit your hole or it's close enough that you can modify your opening a bit then, yes, it will work.

It's close. Looks like I'd have to cut a half inch on the top or bottom and about a quarter on the side. I guess i should remove the old vent and make sure no aluminum beams are in the way. I wonder if a stud finder would work?

Not with aluminium.

Bill.Satellite wrote:
That depends upon what style door you have now. The unit shows:
Cutout measures: 20-7/16" x 10-3/4" x 1"
If that will fit your hole or it's close enough that you can modify your opening a bit then, yes, it will work.

It's close. Looks like I'd have to cut a half inch on the top or bottom and about a quarter on the side. I guess i should remove the old vent and make sure no aluminum beams are in the way. I wonder if a stud finder would work?

That depends upon what style door you have now. The unit shows:
Cutout measures: 20-7/16" x 10-3/4" x 1"
If that will fit your hole or it's close enough that you can modify your opening a bit then, yes, it will work.