This was welded up for me by the folks at South Shore, up in Canada.

I went that route because the ready-made (i.e. hinged) brackets really didn't fit well, nor get enough of a purchase on the sharp angle at the back of this mast cross section.

The toggle is Massive!
Quite a surprise, since the bracket itself is only 1/8" thick. I really don't care if the toggle breaks, but
I really care if the bracket breaks off at the mast!
Which is easier to replace?
Well, actually, neither one..

If I had to do it again, I'd probably find someone local. There is value in making eye contact with the person doing custom work. The bracket wasn't level and flush as it fits against the mast. (Note the large caulk seam at the top.) The two bolts that are directly behind the bracket are flush and hard, but the edges curl up a bit. To be real, here, it only cost me $250 US, which is less than I'd have spent trying to do it any other way.
On the other hand, I'd have spent more to get the job done "just exactly right",
since I intend to keep this boat.

If it doesn't break in the next twenty years, I'll be proven to be an anal-retentive idiot.
However, by then I hope I won't be sitting here playing with web pages!