I did not obsess on precise placement of the tubing; I used screws to hold the tubing against the boat (thought this would be hard, it wasn't), eyeballed it a bit and made some minor adjustments, and then called it good:
Initial bogging to allow removal of the screws:
Fillet buildup of one of the rails:
Poor-man's vacuum bagging was done on all four rails:
With two-three layers of glass in spots (due to overlaps, etc) the laminate wanted to lift quite a bit - I suggest being conservative with the fillet radius. Real vacuum bagging would have been useful here if I felt like taking the time to do it, but instead I just baby-sat the laminate keeping the glass in position until the fillet material started to take hold. I still had some bubbles that required injecting with thickened epoxy, but nothing too bad. End result after cleaning up excess tubing looks pretty good:
Glad to have this behind me... :-)
Happy to report that all beam mount exteriors are completely glassed as well. I have started fairing the cabin sides to prepare for window cutouts, using the notched-trowel method. Finally, I am also working on an outboard engine mount. More details soon...