I would probably hang it up drive side out and think about it for a while and at least have it as wall art in the interval.

There is a minor complication as that region probably has chrome plating under the paint at the seat lug and tube.
Burning chrome is bad toxic.

Mechanical removal of the seat tube by reaming and grinding would probably be the way to go and silver to replace.
As stated earlier by Michael Angelo, that road is not cheap even if you are at a zero dollar cost basis now.

A seatpost with extended insertion would be the thrifty way to go. Replace the tube later if the problem expands.