On a website that offers materials for repair and upkeep of trailer homes, I came across this:

[Linked Image from mobile-mart.com]

The seller lists it as a "self contained" receptacle.

Has anyone ever had to deal with these beasts? Are they well-built devices or over-priced, easily-broken garbage?

They look like they're designed to be flush-mounted to the wall instead of surface-mounted (which is what most "self contained" receptacles" I've seen are).