Hello,
I have and use an Airhawk R, it is great. The R has the center line area relieved so there is no weight on the tailbone of prostate.
Before I bought the Airhawk R I was good for about 250 miles, or a little more. Using the Airhawk R I was able to ride Seattle to Reno in one shot, just stopping for gas.
When adjusted the Airhawk seems like it has almost no air in it. But it works.
Another thing I did was raise my seat. A lot of people seem to set the seat up to be flat footed when stopped. Focus on riding position.
With the seat up my heals are just shy of the ground. Raising the seat moved some of my weight forward under the thigh meat, and straitened my legs out a bit.
Just he seat adjustment added about 100 miles to my day.
The Airhawk R more than doubled it.
FYI - I am 5'10" @ 185lbs
Other farkles that helped with a 750 mile day:
Cee Bailey +4 high, +2 wide windshield
Go Cruise
It was 90 degrees Plus with ATGATT. Opened all zipper vents and poured water down back and front when stopped. BIG difference.
Ride safe.
Fido T Dog