Don't dismiss this so rapidly. You can easily find SS 316 theaded coupling with design loads of over 1100lbs each. In my case the keel is 4100lbs and has 6 or 7 bolts, plus the epoxy filling in the keel to hull joint, plus the fiberglass seal on the outside. Both of these reducing the stress on the bolts. I think that it can be a simple and elegant solution if implemented correctly.
For me it remains a viable option if the original bolt is not corroded at the base.