I know this thread has been resting for a while but thought I'd wake it up again with my own input. After meeting up with another 29MV owner in my neighborhood who had done the adjustment, I decided to go ahead and give it a try. Purchased a 7/8" ratchet wrench and made the adjustment. Made the adjustment by unloading the Helwigs with my levelers. Went just peachy until I got to the last shackle. That one gave me quite a hard time trying to break it loose but finally got it done. It'll be interesting to see how the adjustment affects the ride and handling. I'll probably take it out some time in the next month just to run it and to verify the handling.
2015 Greyhawk 29MV
Honda CRV toad with Blue Ox baseplate
Ready Brute Elite towbar with braking system
TST 507 Flowthru TPMS