Here's a super simple way (I hesitate to call it a mod, even) to make the cargo light a little brighter. It's not a huge difference, but every bit helps.

The light unit has no reflector as part of it. About half the light from the bulb goes into the car interior, and about half of the light is lost in the plastic trim bits where the light is mounted. Making even a crude reflector of sorts will direct more of the light where you can see and use it. (If you have a replacement LED bulb unit, this is much less of an issue because LEDs are inherently somewhat directional in their light output.)

1. Pry off the cargo light unit, and unplug the cable. It pries off with a screwdriver or butter knife or whatever.
2. Apply aluminum foil tape, such as is used for HVAC ductwork to the visible plastic bits inside where the light unit fits. It's not necessary to be especially neat about this, since it's all covered up anyhow. I ended up using something of a patchwork of bits of tape. (This foil tape is not ordinary duct/duck tape with a cloth substrate, but rather adhesive lined aluminum foil with a peel-off paper backing over the adhesive. It's handy stuff for all sorts of things.)
3. Reconnect the light and pop it back in its mounting hole.

It doesn't get much easier or less expensive than that.

 

Was the output of the light bothering you? That's pretty creative! I bought a couple led book lights at the dollar store mounted them in spots I felt to dark. Hatch, glove box where ever.

 

I replaced mine with an LED bulb and that made a HUGE difference, not bad just a few bucks + shipping. But I'll definitely give this a try as well.