“Two is one, one is none.” I wouldn’t limit myself to just 2, especially if as you say the stakes are so high.
A bunch of years ago, I tagged along to go with someone to The Tunnels, which was essentially an out of the way way abandoned but rather “unique” mine. You can be fine for a while, but when walking (slowly) what seems to be an endlessly long featureless underground corridor, you’ll suddenly get a panic attack and feel the walls closing in on you. Like everyone does, including some spelunkers who laffed it off beforehand.
If you ever went out in total darkness to, say, an old airfield, again wide open and otherwise featureless, and even flicking on the highbeams lights up almost NOTHING, you’ll know what I mean.
I only had my Magbulb-converted Taskforce light for close-in snooping, and a 3D (or maybe 2D, forgot) Mag on tightest focus. And assloads of spare cells (a change of cells for the Mag, and an extra 8pak of AAs for the Taskforce). And even then I felt nekkid.
Oddly, the Mag was exceptional for shining down the loooooooooong corridor, as it didn’t waste much light lighting up the immediate area in front of you.
The Taskforce was surprisingly good (for back then) as an all-around light, despite being quite anæmic.
Today? At least a headlamp like a D25, plus a huge powerbank in case any light needed charging. Definitely an Überthrower, like maybe a UC20, to see down long corridors. Definitely a 21700 light like the TS21. Both of those are new additions, and I’m really digging ’em for that they are.
Definitely my MH20 as an all-arounder, that’s also able to be recharged. Worst case, I could use that or the D25 to recharge other 18650s.
All this would be in a backpack, along with things like “energy bars”, and even a few bottles of water, and other Just In Case stuff.
No doubt I’d find room for a WK30 for both red and UV. Fluorescent dye and an applicator (eg, squirt bottle) can surreptitiously mark where you’ve been and lights up like fire from UV. Plus a coupla smaller UV lights (eg, AAA), also Just In Case.