my thought a larger area , for the sub assembly of the braze on onto a steel base, then a pop-rivet on either end
of a larger oval base,, you could epoxy it and then set the pop rivets while the epoxy had not yet cured.. **
I have a piece fabricated in nylon with a front derailleur stop in it that is crewed into a riv nut on the underside of the downtube.
It also functions as a bumper stop for the fork crown to not swing too far..
** Linear Recumbents used the pop-riveted on bases, of steel housing stops , in making their bikes , with aluminum rectangular tube frames..