You may already know, but SPA Defense used to sell the Novatac SPL-120 SPA Defense weapon light kit, that included a Novatac light and the mount. As as far as I know a number of these were issued to the US Army.
Video here:
Novatac SPL-120 SPA Defense weapon light kit mounted on Magpul Scout bracket
I know
@jon_slider has one but just the flashlight I think.
[Edit: actually I see he has the mount and some info about it too, here:
https://budgetlightforum.com/node/62120]
Anyway, IMO HDS would probably do well if they sold their own mount (or a "certified" 3rd party mount). They could then eat into some some of the sales of Surefire, Malkoff and Arisaka Defense.