Silver soldering issues

You could try a map gas torch. They get much hotter than a standard propane but not as hot as oxy/acet.

I silver soldered a bung fitting on an antique ford tractor gas tank a couple weeks ago. The silver solder was in stick form like a welding rod and does not have its own flux. I used liquid plumbers (oaty) flux from the hardware store....worked great. I used oxy/acetylene with no problem.