I've dealt with the same issue. The local marina has started to aggressively measure boats and will allow no overhang on a 30' slip. Otherwise, you get bumped up to a 34' slip and at $10+/ft, it adds up! What's fascinating is that there are many J/30s in the marina not subject to measurement because they've been in slips.
This may be obvious but one option is to ship/stow the tiller hard to one side while in the slip. This effectively reduces the length of overhang by the rudder a fair bit.
- Jeff
