the answer is no, cannot tie into existing vent.
people die after installing gas heat systems incorrectly. usually from CO poisoning
existing is in the upper most floor of a building ? risks are already at maximum
that new heater has to be 100% new install with separate everything
or dump it...
go to MTBR forums lighting sections...for low budget but wicked nice lights
there is a ton of info on cheeeep but reliable chinesium lights, like the yinding...etc...
plenty of lumens, all generally 40-70 bucks. and most are 8 volt so you can use your own 4x18650 holder
with quality cells you...
I've seen these Corollas and they all (the ones I've seen at night)
have a cutoff which appears too bright 1/10 the time. when corolla goes over simple road imperfections will glare you a bit
but when you get closer (60 yards or less) it normalizes ....I think it's inherent in the assembly or setup
I have a McGizmo Haiku I bang around everywhere
I have a DLC Rainbow Killer that rolls around in the toolbox and is used constantly, still looks great
so, no shelf queens except one. Dam Blocky Boy. that one remains waxed and rolled up in a bag.
alkalines have tons of capacity, you are wrong here.
the problem with d cells is they weigh a TON vs comparable output from lithium, and they have lower volts. but capacity they have
you'd likely need something custom for this purpose..specifically tanker duty
the receivers would need to vet out any changes, plus approval from brass
finally, your special light fails. now what ? the board with filters can be used with any light
I would choose the highest output possible for the form factor
I can always cover up or shield output when I want less. but you cannot summon more from some weak light