I've recently installed this box at our fish camp. The quality is great, but you can't close the door with the UMC plugged in, which I don't see as a big deal. Although, I might make an extension to push the door out a few inches to make that possible. Connecticut Electric CESMPS54HR 50-Amps/120240-Volt RV Power Outlet - Amazon.com It's mounted about a foot away from the breaker box directly to the power pole using PVC conduit and some leftover 6/3 from running the house's garage outlet. A+, Would buy again.
I use the Eaton CHU1S, because it opens from the bottom and will hang over the plug, providing more protection against the rain, and they're just under $30 at Menard's or equivalent. These (Connecticut) boxes are good outdoor boxes but are intended for more flat plugs so you can close the box over the plug. Eaton 50 Amp 1-Space 1-Circuit Temporary RV Power Outlet Box-CHU1S at The Home Depot
I saw that Eaton box, but the large opening at the bottom when not in use just screams "wasp nest". And since this is a site that gets visited only every few months, the last thing I want to do after getting there is to open it up to that kind of surprise. The CE enclosure only has a small square that I've put a piece of PVC pipe over. The outlet is recessed enough into the box to provide cover from rain, so I'm not worried too much.
I can understand the wasp concern, although I can say that in the roughly 10 I've installed, I haven't come across a wasp nest in there yet. Just a preference, I've used a couple of the Connecticut boxes too. Given the wasp problems I have, I keep about 5 or 6 cans of killer handy.
I got tired of the wasp nests in my outdoor boxes so now I roll up some paper towels that I close behind the door. These block the slot at the bottom. No more wasps (except in the door panels of the ICE cars that I don't drive much anymore!)