If a tunnel is that long that a light is needed, then GPS will almost certainly be lost.
Then as it’s dark it will go into atti mode.
Better pray drone controller signal is maintained (get in front of it at other side tunnel opening) as if screen view is lost it’ll be bye bye birdie.
That said, the OP might have work to do and be capable of flying atti / maintaining signal LOS.
AIR 2s could handle a range of decent lights, be it single or double (for balance).
A few from doing a Google search for >
Air 2s drone spotlights lightweight
Drone strobe lights DJI Drones anti collision lights drone spotlights uas strobe drones dji m30 m300 mavic air mavic mini autel robotics
www.firehousetechnology.com
Lume Cube Lighting Kits give drone pilots the chance to pilot a spotlight in the sky. We took the Mavic Pro Lighting Kit for a spin to see what all the fuss is about.
www.dronelife.com