Sounds a bit tight to me. Props don't stretch much but they do flex and if that's the top then I would sure be concerned about how much clearance ya have front to back at the prop tips.
2" just sounds a bit too close to me.
This is a good discussion point, if we can get a moderator to move it to the Airboat Talk thread instead of here in the Where To Ride thread it might get more and better comments.
Scotty