What Excaliber said. My primary safe is in the master bedroom closet. The closet is "L" shaped with the back running underneath the staircase, so about half of that part of the "L" has no clothes bars or shelving (here I am needlessly explaining how I got away with using up closet space, but it's a shared closet). The safe is mounted at the end of the clothes bar, so taking up storage space but not hanging space.
Anyway, the overhead lights run only along the other, longer, front part of the "L". So what I did after living with a darkened safe for a few months was buy an LED lamp that had a tactile touch on/off plus a dimmer control. Mounted that on top of the safe and it has a pivoting arm so that I can swing the lamp back out of the way or over the front of the safe. It also has a dimmer control; I don't need a lot of light there, so I keep it set to low lumens. There's a light inside the safe but that doesn't help until the door is open.
Made a really big difference. All I have to do is touch the base of the light and the lamp switches on or off. I can easily see the front of the safe (and the ammo cans stored up under the slope of the staircase), and the small light swivels out of the way once I'm in the safe and working with its internal light. Speed of access is slowed only by a quick touch at the base of the lamp.