Update**
I last posted to this thread about a week ago when I ordered the Poly-Weld.
Well, I finally got it and jumped head first into the repair.
Site preparation was tedious. First a spray down with Goo-Gone to remove dirt and grime, followed by sanding and flame treating the repair site. Poly-Weld is very difficult to work with. The consistency is somewhere between cooling tar and molasses. It sticks to everything and *nothing* will get it off your fingers, clothing, etc.
I picked up a glazed tile and narrow compound knife thinking I could apply it much like joint compound. Big mistake. A plastic lid and narrow wooden stick would have been much easier (and more precise).
The first site (the "big gash") was the most labor intensive as I used fiberglass mesh to reinforce the repair, which also concealed the gash making it difficult to ration material. In retrospect I think the mesh may have been overkill altogether. The second repair site was much easier - a 4" horizontal clean cut. I just pasted over it and was done.
With just my luck, the temp in the north-east dropped to around 40F and will probably stay around there all week. At this rate, the "24 hour cure" time will likely be 24 days! Ugh....
Whenever it does cure, I'll sand and apply a second coat. If the repair holds, it would have been worth the heartache. I mean, $72 for 3 tubes of Poly-Weld and another $20 or so for miscellaneous materials is a far cry from the cost of tank replacement.
Stay tuned....
