I am also in the "keep your element threads/nut outside of your enclosure" camp. I haven't posted mine in the show me your element thread because I'm not quite done yet, but here's what I've got so far:
Boxes are reclaimed junction boxes off scrap electric motors, modified to take a cover on both sides. I drilled a hole in the cover for the element contact block to fit through, then welded the element nut to the outside. I put a bead of silicone sealant on the inside of the cover around the contact block just for good measure.