[GORDON HUMMEL]

I had the exact same problem about 2 years ago. I was looking for a replacement & Lowe's had a floor model Whirlpool for less than $300 delivered, in black. This is the second time I've had this problem in an RV & the AC unit was the best way for me. It is quite a bit larger and cools much faster, even freezes when is 100+ outside, which the original unit never did. It is quiter than the ice maker!
I have 2 non deepcycle 8D's that came with Newell. When camping without AC, I can go +/- 18 hours & that includes running a 42" LCD tv on the batteries.

As I recall I had to enlarge the cabinet about 1/2" on each side.

Also I added a rubber seal on the sides & top, that attaches to the cabinet walls & seals against the frig when you slide it in. I think it was meant for a garage door bottom seal.
I closed off 2 of the 3 vent openings in the exterior access door, & closed off 1/2 the roof vent.

After I leveled it, I retained it by some screws in the back to the compartment floor.

Also I put in a switch to shut off the freezer defroster when I run it off the batteries.

Lastly you will need the fabricate a door(s) lock for traveling. I drilled a hole between the 2 doors & used a spring loaded locking pin which retains both doors. Just have to remember to put it in before I travel!