You should put in a request in the modders forum over at Candlepower Forums.
Personally, I don't think any kind of clicky switch is going to work; you should accept the fact that a twisty UI will be simpler to design and also more durable. It can be made workable, there just have to be enough threads to keep the head from popping off and to allow o-rings for water sealing to be further in under the back edge of the head. Also, with a twisty design, you could employ a quantum tunneling circuit, which IIRC means the light will get progressively brighter as you tighten the head, allowing for practically infinite adjustability.