Hmpf?! Well, Gunner. I suppose since it's a 1:32 scale you may have enough room to attach it now...clean up seams you may have to treat...and then paint without any problems. Personally, I'm doing the 1:48 version...and I hit the place where the wing is meeting the fuselage with the gloss black first, then attached the wing...then touched up a few places along the seam of the wing root and followed up with the gloss black to finish along the wing/fuselage. You can see that up above. It worked out okay for me. I guess it really comes down to your painting methods/paint scheme.
For instance, I'm considering throwing down some White Aluminum first and taping off certain parts around panel lines to allow that lighter color to show. The radiator is the only part that worries me most, but I can handle doing what I have planned so I'm not worried about not being able to reach it well later. If you're throwing down more than one layer of color, then I'd give it some consideration. If your taping skills are strong, then I say go for it. This is my first mustang though. I'm sure others out there have found some pretty solid ways to negotiate that little snafu. =]
Seems like you have things under wraps from what I already see. I say just go with your gut. ;]