Hi Grover,
regarding your harness, I have done a bit of rock climbing, and your harness looks a similar sort. I think you have to ask yourself what is it for; a)safe suspension, b) allowing flexibility of movement c) supporting your back. the harness you show does a and b, not c, but I feel that back supports are to keep the back still and protect it from too much movement. If you are starting with a healthy functional back, then this support looks fine. spines are designed to be flexible, but beware overloading them!
Not very nice weather for arborists just now.....