We install them on the outside all the time, just need a NEMA3 rated switch.The only thing I see is around here we are required to have a disconnecting means before the switch, so you would need a disco and a transfer switch, but I agree with Mike(trumpy) talk to your utility, and AHJ before making any plans, or quoting any prices. We install lots of them just as you describe, with a cam lock plug for a portable genset, so the owner can move the set to other locations.
