I pondered weighing in on the epoxy approach, but hadn't resolved it in my mind before rtrafford finalized his method. I was leaning towards a flexible material. As a an un-gifted amateur woodworker, I'm familiar with woodworking methods that compensate for expansion, like breadboard ends. Those are only glued at the center boards to allow the longitudinal boards to expand/contract across the grain, as an example. The thing about toe rails is that they are securely fastened to the structure and protected against moisture intrusion by the bedding and topcoats, so expansion and contraction should be very slight, especially if the fasteners are very near to the butt joints. I guess we'll see if there is enough movement to crack the epoxy over time. I would caution about the catalyst used with the West,though, as the fast catalyst discolors very badly in a relatively short time. The 207 Hardener should be the best. West cautions against using 205 or 206 for clear-coating. The approach of making a jig and performing a precise repair is great. Besides being professional and workmanlike; If the joint doesn't perform satisfactorily, the same jig can be used to repair and redo. Please let us know how it turns out, and also please mark your calendar to give us an update! We can all learn from your experience.