I don't love Rudy as a third wing on this team, would like him much better as a starting SG. Ray Allen will be playing a lot of SF with that roster, which scares me at this point. The other value Rudy would have is that you could go Rudy, Ray, Pierce - with Pierce as the half court play maker and Rudy or Ray bringing up the ball and that lineup would work at least as well, probably better than the Allen, Allen, and Pierce we saw a lot of in the playoffs.
Roster wise you could live with something like:
Pierce / Posey
Allen / Rudy
Rondo / AB
Where Pierce, Allen, and Rudy all saw 30 minutes a game, and Posey or AB were deployed as situations dictate. Then you'd have Rondo at 35+, that get's you to 125 minutes, with 23 minutes left between Posey and AB. It's managable.
Long term it let's you move Rudy to starting SG if Ray Allen leaves after this year - or if you get a chance to trade him for better value.