UPDATE - Did the install today. 2" spacers up front. I left the stock rubber spacer in there as well. Teraflex spacer on top, OEM spacer on bottom.
I had to extend the upper spring mount down for use with the Air Lift load support bag that I was installing as well. I couldn't do the hockey puck trick because the fill stub of the air bag must go down through the lower spring mount, which gets drilled out. I used 1" galvanized pipe for the extension. It fit up inside the bump stop holder. I did have to tap the hole that was in the bottom of the upper spring mount. The pipe spacer was 2-1/2" long. I used an M10-1.50 X 100mm bolt and some 9/16" fender washers to mount it. I also used some plastic caps to cover the bolt head, and protect the bag.
The rear shackle install was straightforward and went according to installation instructions. The tail pipe did have slight interference as expected.
Currently I'm still running 235-75-15's, but plan on 31's in the near future.
After a brief run around town, including speed bumps - this is what I found:
Stock Shocks seem to be fine. I did not bottom out the shock. First a slow trip over a speed bump, then one at about 10pmh.
No rubbing at full steering lock under slow conditions, or at 10mph and then braking hard.
Both conditions above were tested with and without the plow mounted.
Measurements (H2F)
Before
Front - 16-3/4"
Rear - 17"
After
Front - 19-1/8"
Rear - 19"
Minimum pressure in air bag must stay above 5 psi. Measurements above are with that pressure.
When the plow is mounted, and raised, the front end sags down to 18-5/8" with 5 psi in the bag. Increase pressure to 60 psi (bag is rated for 100) and I'm back to 19-1/8".
This seems to work great. The ride is not great, but it's no worse than what it was pre-lift and support.