Have you considered a Cycle Stop Valve?
I currently have a Pro Source "50" gallon tank which I believe holds much less than that and my house has a lot of bathrooms, plumbing, etc and I have irrigation. I always have thought that it cycles quite a bit, I haven't checked the pressure but don't think it's that as much as the demand. One page I read said, buy the biggest tank you can afford and fit, and then another said this is a bad thing.
I also have a pinhole leak on the manifold coming off the tank and have made some other upgrades so thought it might help my pump life and would be easier to replace the tank and manifold.
The tank I looked at was a extrol 82 or 86 gallon, does this make sense? Or is bigger not better?
It's just artificial head pressure. no different than if the pump were working from a deeper water level. wellxtrol is good tanks.. the pro source not so much.
Best thing is to let them play with this graphic. http://www.cyclestopvalves.com/simple/home.php
These kinds of things were not available 20 years ago.