S
spacecaser
Don't forget to allow for the socket/base which the bulb plugs into - I'm not certain exactly, and different models etc, but I'd allow an inch or more for that, and so you can actually remove or insert the bulbs.
Thats funny you say that because I was thinking I might just solder the ballast leads to the bulbs LOL. Makes for pain in the ass bulb change but would allow me to use 36w PL-L in my case:} (17-1/2" interior length)