Oops, color me embarrassed,
I just reread your original post, and realize I somehow misread what joint it was you were talking about, and thereby missed the jist.
To answer your real question - No, as I see it there is no way to peg off and effect draw in a halving joint…
For this reason I have long chosen to forgo a pin at this location and instead use a variation with undersquinted shoulders, recently nicknamed the “handshake joint”. The idea being, to allow the joint to shrink together and into itself as it seasons. If there is some distance from the ridge to a butt purlin or a purlin plate, and there is a safety issue at raising or enclosure I will apply some kind of “gangnails” type metal fastener to avoid lateral dislodgement until enclosure is applied.
If a peg is not needed for tension, and might lead to a joint shrinking apart and not together I see no reason for one at all. I’d rather know the shoulder is bearing the opposite rafter, than worry that the pin is forcing only that material above the hole to do more than it’s share and in effect potentially split one or both halves. I see this as an issue in all high shrinking species
Let gravity keep you and the frame looking good.
