It would be possible to insert silver solder foil between the mating parts to give the correct gap for the solder and then insert rivits with the heads on the outside and just lightly deform the inside of the rivit to hold it in place. The whole lot could then be soldered.
You would need to ensure the flange widths were suitable for silversolder and if you intend to use in public have a word with your club inspector first as if the barrel is a lap joint ne may want to see a butt joint with strap.
J