Welcome,
I think the "tee" option could work, but mine is just same as Loki9's setup.
If you put in a tee, then you might have to balance it a bit. I don't see any real technical hurdles though.
I have a Columbia too. A '68 36. Not really similar boats but family
.
I read that the mold for the early 29 was taken off a wooden boat and the lines in the hull were left in the new mold. I found the story somewhere out there in internet land. The boat next to mine in Homer Harbor is a '66 Islander 29. Does yours have lines like a wooden boat?
With all the genetic pooling of boat designers and plants back then I can imagine they might be very similar.
Russ