I would have done is a poor man's decoction and drained off the amount of boiling water you would need to hit your mash temp and boil that amount of runoff, after vortlauf-ing or straining somehow of course.
You just convinced me to get a propane spare. I can't imagine this happening to me.
Primary: Centennial Blonde
Secondary: Souring pumpkin ale (2011), Belgian Maple Quad, Anniversary Old Ale