Tonight I took the tapestry off of the loom. Once the piece was relaxed, once the tension was normalized, the selvedge issue became much less obvious. That is good to see.
I tied each pair of warp threads together in square knots. Then I started weaving the loose ends back in. I used the threaders I mentioned before with mixed results. I snapped one right off. Then I tried a twisted beading needle, then a large gauge bead threader. I ended up going back to the punch embroidery needle threader and just being careful, careful, careful as I pull the yarns back through the weft.
I managed to get maybe a third of the ends woven in before I got tired of doing it. I will probably finish weaving them in tomorrow. Then I will have to figure out what to do with the warp ends. Now I am going to finish building the smaller loom and maybe warp it.