Have you throught of a 14500 flashlight as the Convoy T2 or Jaxman E3?
Both can be easily modded with 17mm driver and different types of LEDs (even triples) and also with forward clicky switches!
I also recently modded an On the Road M1 (16340), that would fit a 15mm driver and takes forward switch with no problem as well! Also, the emitters can be modded easily!
And you also got Sofirn SF14 and SF10 that work good as hosts 