I did have early plans to put Batman in UVR4 and have him come out immediately after Cap. I mean, if Marvel and DC are so overprotective that they wouldn't give either character leeway (ie. JLA Avengers or how Cap lost in Marvel vs. DC), why not have the UVR voters figure it out?
I dropped the idea due to the fact that Batman would ultimately get involved with the backstage shenanigans and I didn't really want to have to deal with that.