Get a good utility and be nice to him! Its all about the cable wrangling. Make sure the cable coming off the camera is not in your way. I usually get about a 2ft+ of slack of the camera(for panning,tilting, booming up and down, Don Juan, etc) and then secure it to the vest by your shoulder and let the rest dangle behind you. This is where your utility comes in. Make sure that he keeps that cable off the floor but gives you enough slack to move around. Its a dance and an art. Practice, practice, practice.
As far as your back is concerned. Stretch before and after. When you stretch before make sure your back is warm. Stretching cold muscles is counterproductive.
Good luck.