Is this concern valid?

Drape a moist rag over the shower body where you don't want the heat.
Use a MAPP torch to heat the fitting quickly, then wipe down the joint
with a moist rag after waiting a few seconds.

Handplanes suggestion will work..... I was concerned as you are about
tape & dope survival but using HP's method I have soldered "near"
tape & dope with no leaks.

btw brass is not nearly the heat conductor that brass is....so heat
the end to be soldered quickly & have "no worries"

cheers
Bob