John at Stout Tanks and Kettles is working on a system for me that uses tri-clamp ports for elements. I think they are just 1.5" TC x 1" NPS.
The camlock solution sounds cool though, I think that would work beautifully. My advice would be to get 1.5" or 2" camlocks, with a female end on the female camlock, then use a hex bushing
to reduce to 1" for the element.
Also make sure to put the male camlock (bulkhead) right through the wall of the kettle then put a locknut on it inside (or weld). That should keep the base of the element close enough into the kettle.