You could conceivably have Riv-Nuts put in the seat tube holes to mount a second bottle cage, but something needs to be done about that top tube! I'm not a fan of internal cable routing, so my personal choice would be to replace the top tube, in which case you may as well skip the Riv-Nuts and get proper bosses brazed in the seat tube.

Alternatively, there are reinforced braze-ons for internal cable routing that might cover enough of the damage and allow proper internal cable routing:



Again, as long as you're doing some brazing, you may as well do the bottle bosses at the same time.