Which MT G2 light?

If you’re comfortable doing a host, there are some for a lot cheaper than the Nitecore. Try a Convoy M21C host for like $30. Takes 20mm mcpcb and 22mm driver, or just buy a M26C for like $8 more and swap the LED for the MTG2. Or go with the L21A host that would give more throw. They’d use the same drivers (boost) at around 4.5 A for the 6v xhp70.2. Get them on the Convoy store on Aliexpress. All take 21700 cells.

The problem is the reflector opening, even the XHP70.2 version is small and will sit over the led

Thrunite TC20. Direct led swap, you can boost current too if you want.
Mike