I would split those GPU's into a few rigs. In my experience, 6 GPU+ rigs are a nightmare to maintain, unsuspecting bugs happen all the time.
I have three 13 GPU rigs with 7 NVIDIA and 6 AMD cards per rig. I also have two more cards in workstations. Works great at the moment with the latest Claymore. I got the cards down to about 100 watts or less each (two are a bit over that) and getting a total over 1.3 GH/s.
The only tricky thing is to stop Windows from pushing updates causing disruptions. I have tried various methods but it appears to be persistent. What works best is to set the network connection as metered.