My buddy makes a little under hood light kit for 4Runners and now after measuring my truck will offer them for 100 series. He'll also have a universal version.
It uses a little pressure switch to turn the light off when the hood is closed and it turns on when the hood opens. Super slick and incredibly bright! There is also a manual override switch to turn the light off manually if you want to leave the hood open for a long period of time. I actually bought 2 and I'm putting the other one inside my rear hatch.
Nice! Always thought no light in the back was a big oversight, and switching all interior bulbs to LED only helped a little.