My method of clapping my hands together in prayer and then metering for EI 12 seems to be working with 720nm IR filters at least for during this heat wave.
also that is hilarious about the metering method. we've seen IR photography before but we never thought about the challenge of metering it........
IR metering depends on time of day, time of year and altitude so you really just gotta find your groove with your location. A smart person would bracket but really it just demands fealty to old Gods.