I would be sorely tempted to pre-paint one of those cable covers and then epoxy it to the frame. It may or may not reinforce the hole, but it will cover it and look pro. No re-painting, no torches.



For soldering, if you aren't confident you can "tin" the back of the fitting with solder, then flux the frame and heat it in place to get that solder already on the part to stick. Won't work if you don't get the frame tube hot enough, though.