I had an older light fixture hanging above my garage door. It stopped working, so I bought a replacement and went to install it. When I removed the old light, I discovered that it had been screwed into a chunk of 2x4 which was just free-floating between the framing of the overhang and the steel soffit. The hole is fairly small, but I went into the attic/crawlspace above the garage and couldn't see any light, so I think it's too small of a space (plus blown-in insulation) for me to come at it from above. Further complicating the issue is that the new fixture seems to be expecting some kind of purpose built mounting plate or bracket of some kind which obviously doesn't exist.
I'm not a fan of this idea but I don't want to hire someone for hundreds of dollars to do this. So I'm thinking I can maybe just fake the funk again, here and cut away some of the soffit and maybe more-securely attach the wood chunk (or make a new wood chunk) and replicate the expected bracket that way.
Does this sound like a good idea and how would you solve the problem?
edit Model: Secure Home HeathZenith 022246