I want to thank everyone in here for the inspiration in building my first 'geek' light. Although simple, it is far more effective than I expected. I still have a couple of tweeks to do..... but the gist is a "malabu" garden/yard housing with a 50w spot, 12v 12 Ah battery which just lights the heck out of the night.
I gave it the first test run last night and it was da bomb

...and just in time. I was running my NightHawk along side of it and the battery on that finally gave up the ghost. Course.... now I have this really nice - purpose built housing and switch to cannibalize. Hmm,
I went with the 12Ah battery since I can also add tail and side lights and I'm thinking a horn too.