You could maybe attach something like a Peltz head lamp with a 3M double sided sticker, but the center of gravity will shift, and you'll probably have to hand takeoff/land. The thing is you won't see anything; even dedicated enterprise line searchlights are not enough to see well at night.
Drones can see decently at night in well lit areas, but on rural areas you will see nothing.
For night flight, drones should be equipped with a IR camera and an IR flashlight, much like any security camera these days, but there aren't any available, so for night search the best alternative is a thermal drone (which is much more expensive than what an IR drone would be),
M2 enterprise dual can be found for around 1.000€, but I don't like the M2 design and the thermal camera it has is super low resolution. M2 Enterprise advanced can be found at around 3K, has a nice thermal camera, but the same, don't like the design as the battery can pop out midflight.
M3T is perfect because it has a thermal camera and also a tele, but is still on the market, so until the M4T release it will be expensive. I've been reserving some money myself in the future when they are around 3K or so.
