That's a nice fan. A little on the pricey side, but im definitely going to keep an eye out for sales or similar lower priced options because i like the form factor of it and would like to use 2 to create 'active air exchange' through my house at certain hours.. thanks for posting it!
Well if the fridge is no longer there then that makes things a little easier because then the window unit never has to breathe the fridge's condenser exhaust. I'm not sure what you mean by all the intake holes at the back of the unit, do you mean the 'air inlet holes' on the sides and top of the window unit for the condenser?
I do plan to revisit the idea on my RV at some point, but in my case the space was not conducive to 'doing a good job quickly' and i was trying to get the unit installed before a trip so i had to abort and go the 'conventional' back wall route even though it wasn't my first choice. I have an older RV project (1968 Clark Cortez, 19f long total) that i will 100% do the side wall mounting on, with no rooftop unit at all, and however much work it takes is what it takes because im not gonna put it anyplace else.
On my actual running RV that i use that has the window unit, i still have the rooftop unit in place even though i sort of hate it. I would consider removing it or at least downsizing it to a low-profile 8k btu unit. I would probably 'downcycle' it to the roof of my shipping container storage shed. If im working in there i'll GLADLY pay the 1500w penalty to lessen my suffering.