Short re-build to Ironman

This is a few years out but I'm just trying to get an idea of this possibility. I would like to finish my first Ironman in late October 2014 (Beach to Battleship in NC). I'm planning on doing at least one HIM the season before this as well as a marathon in either fall 2013 or spring 2014.

However, I will be doing an activity called Drum Corps. Essentially I would be with the corps from the middle of may til the second week of August. Leaving 11 weeks before the IM. Drum corps is a physically intensive activity however not as much as an ironman and there would be no cycling or swimming. So my question is if I was in shape for an ironman before leaving on tour, would I be able to rebuild that in the 11 weeks before the race? Again, I would still be fit from drum corps but I'm sure I won't be as fit as when I left to move in with the corps. Thanks for your advice!