As far as drilling holes in the mast, I just don't know. I'm not an engineer and pretty much just fumble along the best I can, that said; certainly too many holes must be bad and large holes must be bad, but all masts and booms have holes drilled for attaching things. I would guess that placing the bail close to the deck, where the mast is supported by the step, would be preferable to placing it higher. That way the horizontal pull on the halyards, from the mast to the cockpit, would be transferred to the step and not to the mast column, perhaps pulling it out of line. I think the bail was installed with the mast in place because there was no compression tube in the mast, but still it worked for many years. I put a length of PVC pipe over the bolt when I replaced it. Of course over tightening the bolt and kinking the mast would be very serious, fatal.
Another option might be to mount blocks on deck, with stand up bases, and through bolt them to a stainless steel or aluminum plate. If the plate ran under the mast so much the better, but I don't know if that's possible.
I didn't use the website to order because his shop is just 20 min away, and I prefer the phone anyway. My invoice says the part # is Hinged base ss 1/4" B HMB M30, 3/4" Delrin plate.
The Delrin was cut to shape to fit tight inside the mast as a plug 4 small holes were drilled through the mast into the Delrin which was tapped for screws. The top plate of the step is held to the plug with counter sunk machine screws tapped into the plug. The bottom plate is screwed to the deck with existing screws. I drilled out the plates and plug for the wire. I have not yet dropped the mast with this rig.
Craig Tern