Stopped by Harbor Freight few days ago and impulse-bought a really cool shop work light.
https://www.harborfreight.com/...ork-light-56163.html
You charge it with a USB charger, it throws a TON of light and lasts for several hours. Drop it on the floor or on top of the central tunnel when you're working under the dash and there are almost zero shadows anywhere and everything under there looks lit up like Times Square at New years. Same thing for putting it in the engine compartment - It throws enough light that it just needs to be semi-near where you're working, PLUS it doesn't throw much, if any, heat.
Should have gotten one of these years ago, and they're currently 25% off, if you're a HF Member.
Here it is under my dash: