I've said this here about 1157 times, but on stuff like this you can use J.B. Weld quite successfully and avoid the worry about welding. You can also use silver bearing solder (Harris StayBrite is best). Do the back-up thing you mentioned, let the epoxy cure well and then simply epoxy the replacement piece in there. 40 years ago I got a crack where the roof joins the windshield pillar in mine. Repaired it with J.B. Weld and haven't had a problem.
