Silicon bronze wire. Lower melting point,and weld wont rust. And maybe more malleable.
There will be warpage, the whole idea is to minimize it. I brazed panels on,way back when, cooling with wet rags as i went. Could feel the metal pull as it cooled. Tried heat shrinking back then too, could never get it. Now i think i could. And now its a shrinking disc, mounted on a grinder. Should look into getting one.