Divorced set up – shock length?

Installed air suspension in my Honda Odyssey and I find the rear to be jarring at times – when I hit a bump or a big dip in the road. I am thinking I set the rear shock length incorrectly.

So I adjusted the length of the shock based on the length of the bag fully deflated, but with no weight on the rear. So the bags are fully extended with no air pressure. I’m thinking now maybe now the preload is incorrect, and I should have pressurized the bag before adjusting shock length. Any recommendations would be appreciated

by jyu2018