Since the loading on the bail is nearly perpendicular to the bolts, all the loading is in shear. Therefore the threads in the carbon are taking a low loading, so tapping and bolting for the bail are not a big concern. Yes, adding some epoxy (I like to thicken it with high density filler in this type of application) will help.

Using a bit of line does work for a bail...but I would not select Vectran as it does chaff (spin halyard strop rubs back & forth on the bail while loaded) and is more UV sensitive than Spectra (like Amsteel...I find it best for good chaff resistance).
The best way to install a line for the bail is to drill 4 holes, 2 per side, vertically spaced about 1" apart on the track. The holes Either the top pair or bottom pair should be about where you want the bail to locate. Pass the line through one hole and fish it through the adjacent hole on the same side of the track. Tie a stopper knot on the end you just passed out the hole. Run the loose end around the front of the mast and repeat the line feed through the two holes, tying off another stopper on the final end. You will now have a bail loop on the front of the mast without drilling holes in the sealed section of the mast. Plus, no knots inside the sail track to foul the mainsail bolt rope. Also very easy to replace the line when needed.

I used to run a line bail on my Alu Tmast. The Carbon mast for the T has a stainless bail installed. So, I run amsteel for the strop and further protect it from wear by wrapping it with UHMW plastic tape.

Mike.