Copper pipe vs. PEX behind refridgerator

[Kayak]

I have a 1975 Overlander with standard Dometic fridge. I'm totally replacing the water system in the trailer, keeping most other things stock. My fresh water tank is now in the front of the trailer along with pump, water inlets, etc. I need to run a water line from the front, down the drivers side to the hot water heater and then on to toilet, sink, shower, and then up to kitchen on curb side. I need to run the water line behind the fridge. I'd like to do it at the level just under the counters, about 24" up off the floor. If I run it behind the fridge at that level will it be so hot up there that it will melt the pex? Do I have to run it along the floor where it's cooler? Or should I run a section of copper pipe behind the fridge so temperature will not be an issue? Thanks for the input.

[AlinCal]

Probably not a problem but do you want your cold water coming out of the faucet warm? I would insulate both hot and cold wherever you run it anyway and would keep it away from heat sources but not for fear of melting. Pex is commonly used for hydronic heating that can have 160 degree water with no problem, rated higher.
No to the copper and pex combo.

[AlinCal]

Just looked at a roll of 1” I have and it’s rate to 80 psi at 200 degrees.