I have 5
broken/collapsed vertebrae and all of my my bone structure has changed due to severe osteoporosis …so very aware of dealing with back pain …
weight of guitar is a very big thing for me…[if weight of a guitar is a thing](With search function lightest guitar if weight of a guitar is a thing
This one I post of the many posts about posture while playing…chairs also feature in many when it comes to preventing or eliminating back problems…I see that while I’m typing, Shane has posted a lesson from the topic I’m posting… … take the time to read everything and…
watch your back 
Good luck and greetings