Whether you use a boom vang to shape your mainsail or mainly to sail more safely, I think a suitable mast plate/organizer plate provides the best way to attach it for form and function. If you are capable and willing to work with stainless steel, you have many options. But for those wanting a turnkey mast plate, the choice is more limited. I have two mast plates that should fit most Mariners without further modification. Online fabricated of 12 gauge, electro-polished 316 SS, the plates have holes for cast tabernacle mounting.
Using assumptions for order quantities and markup that might be typical of a chandlery, price is $145 each. Can ship in USPS flat rate padded envelope at $11.10. PayPal or Zelle.
Walter Pearson
pearson1854@comcast.net