I’m sure it will be fine considering how many work trucks have slip tanks in northern climates with exposed pumps
I worked out in the dakotas we ran external tanks in the beds of our trucks. Never had any problems, just treat it with some howes and we were off
Where are the fuel pumps located for those in-bed auxiliary tanks?
I'm just noting that the fuel pump is exposed for the spare-tire tank. The Aussies generally keep their fuel pumps in the fuel tank to avoid that very issue.
Maybe it's not an issue in reality, but, in concept, I'd prefer to have a the fuel pump enclosed in a safe location rather than exposed on the frame rail.