Let's be honest caterina bootloader is a colossal pain in the butt most of the time.
You have to perfectly time everything to get it to flash. Half the time the software reset mode doesn't work, and you have to take everything apart to get it into reset.
And let's not forget, they're easily bricked when it inevitably crashes.
Pick yourself up a couple of pro micro's with QMK-DFU pre-installed, at the most reasonable price around.