I used one of
these on an 18650 box for quite a while with no problems. They seem to be sturdy. They're big, if nothing else.

You might give it a shot. You can check RS's website & see if they have it local. If not, check out
Mad Vapes. He's got some good switches there.
Have you tried using a 'store bought' 5v pass-
through for your dry burns? Hook it to a 2A wall wart, should give you the power you need.