Seems to me the answer is to leave the first few inches unwrapped?
The next time the engine is hot, set the idle rpm up to around 2200,wait a few seconds, then start hunting around with the IR gun, and see where the pipe temp starts to drop. I my experience the hottest part is from about 1/2 inch past the flange to just after the first bend. Plus it'll be so much easier to wrap...those tight bends are... um............ painful.