I have a few strategies. Longest flight so far was like 16 or 17 hour leg between SF and Singapore.
Inflatable Travel Pillow for Airplane, inflatable Neck Air Pillow for Sleeping to Avoid Neck and Shoulder Pain, Comfortably Support Head, Neck and Lumbar, Used for Airplane, Car, Bus and Office (Grey) https://www.amazon.com/dp/B07VHPFK5B
It makes item 1 less effective, but it is nice to be able to stretch and stand so if you can get an exit row on a wide body plane, you often have 5-6 feet in front of you and easier access to walk around a bit. Mentally, I definitely feel less “trapped” here.
If you happen to be able to get on an Airbus A380 for your route, I love being able to walk up and down the stairs in the back.
yeah last i checked the spinal fusion surgery is up there in top 5 surgery's to avoid if you can, I've wanted to get it too but I cant afford it XD
It isnt a permanant fix, but you can sometimes find a good brace that corrects it temporarily while being worn, it helps prevent it from getting worse. but its nice when you can hide it under a shirt or nice suit at formal events.
Ive been using these ones
https://www.amazon.com/gp/product/B07D4GG6YM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Get one that wraps around the stomach,
the ones that only wrap around the arms are hot GARBAGE