Ai, zoomable headlamps all tend to be in the ultra cheap segment, so not waterproof, bad PWM and gritty threads. Led Lenser does some zoomable headlamps but I do not know if their optics produce the nice even flood that you are after, especially the Optisolis may not work in their optic, and they are usually not easy to mod.
An alternative that should give great flood could be the Armytek Tiara C1, it works on 18350’s, has a protruding switch for operation with gloves and is 10m submersible. It has no spot mode though and as I understand from you these are a pain to mod
The doctor didn’t like the Tiara I showed him because it’s too floody and off center. It’s ok for general surgery but for ear or mouth inspection it’s a no go. He couldn’t see the patient’s ear canal properly.
I saw Fenix HL40R, looks good but I have no idea if it’s mod friendly.
Nextorch has a headlamp zoomie which should be of good quality. Not sure if it meets your requirements though. Especially when it comes to moddability.
Thanks I’ll look it up. This Nextorch website has so many interesting EDC. The Glootoob is very-very useful for my fishing lure!
Side track shopping begins…ugh….