dude, this may suck. I'm sorry to just be catching this now. follow me on this: make your forward and aft keel segments each like two inches longer. notch them and the double keel segment so that they have two inches of overlap. then, when the ribs go on, and everything starts coming together, fill those overlaps with epxy or something to make a rock-solid bond. Mind you, when the hull is together, your chances of breaking the ship's back are minimal. the keel isn't as critical as a load/strength bearing structure as it is in full scale. the surrounding hull can absorb a lot of the strain/impact stress, especially since you'll be fiberglassing the hull.
Just saw this build. I agree with anvil above, have the forward and rear keels overlap the middle keel sections by at least 1 rib station. Maybe 2. If you do 2, have the notches opposite so that way it locks together. Aka if the front keel meets the middle keeps at ribs 8 and 9, have rib 8 slotted from the top so the front keel slides down onto it, and rib 9 slotted from the bottom so the front keel goes up into it. CA + Kicker is fine for holding the framing together. You are going to go back over everything with marine epoxy before you fiberglass the bottom, and then once you fiberglass the bottom that becomes the primary structural part of the boat. My wooden Jean Bart has had most of three ribs removed and about 6" of both center keels and there has been no noticable decrease in strength. Good luck on your build.
