I know the 4th wall breaking and everything is one of the features of Deadpool's character, but as someone who could be considered general audience in terms of Deadpool (I've read 3 Deadpool comics, so I hardly qualify as an expert), I think that kind of thing might be a bit awkward.
I mean, it's cool in TV show comedies like Family Guy or something, where it's not meant to be taken seriously anyways, or even in a comic book, but in a big time feature film, I dunno if it would work as much.
What I DID like, was an idea I heard on here (pre-leak, so it has nothing to do with the actual film), was that in the final battle, we'd see the experiments on Wade begin to fail since he was released into battle before he was ready. He'd lose his optic blasts, and all the other powers he had, except his healing factor, which would wonk out. Logan would be able to defeat him, but wouldn't destroy him.
The incident, both his powers going haywire, and getting sliced up by Logan, would make Deadpool go mentally insane, and part of his insanity would be walking around acting as though he were a character in a movie.
I think that would be a rather creative way to incorporate his 4th wall breaking. He's not actually acknowledging that he's a movie character - he just THINKS he's a movie character because he has gone insane.
So in his spinoff, he could walk around saying stuff like "Damnit, why did the writers have to make me face off against THIS GUY?!" and it'd be funny because he'd be breaking the 4th wall, but he'd just be seen as insane which he already kinda is anyways.