Search on here for Martin D White, he makes adaptors for light tubes. I got him to make me a single CR123 tube for my Malkoffs, I sure he could help with something for you.Not a bad idea. A solarforce single cr123 host with a tape switch might be the way to go for this....
Would love a more purpose built housing that's even shorter than a single cr123, but my searching has turned up nothing so far.