I'm 5'6.5 and using 120mm stem. Specialized Allez Sprint size 49, so long and low geometry. 38cm bar, 165mm crank. I used this bike on multiple 5 hours 100 miles rides on bumpy farm road.
It takes a few weeks of plank and other core body work and a few rides with sore neck until i don't notice the extra reach anymore. At this point, i feel like i could almost repeat the process and try to earn upper body strength for 130mm stem or lower handlebar height.
pictures here:
viewtopic.php?f=3&t=152452&start=195#p1505764
If you want to see someone short with long stem, check Caleb Ewan. 5'5 with 150mm stem, deep drop bar level with front tire...
https://www.bikeradar.com/features/pro- ... t-gallery/