I don't have a delicate's woman butt, but I feel the pain when I go thru a bump, so what I have done is just stand on the pegs for 1 or 2 seconds while I pass the bump.
I have not tried standing on the pegs at speed, for momentary relief, but when the rear pain has set in I do stand up when going over speed humps. Even with arthritis, the best suspension is the knees!
Instead I have a gel pad that just clips on the seat (with a velcro straps that goes around the seat for added security) that I use, but it only gives limited relief. Better than nothing, but not really a solution.
Previously I have tried a bean filled cushion from www.bumbags4bikers.co.uk
, but that just ends up with the beans all at the back. Somehow they defy gravity.
I have also used both together, but after a while even that makes hardly any difference.
But today I took delivery of a Tourtec air cushion, so hopefully that will help. However I never thought to measure it, as the eBay page listed our bikes as being compatible. And I have not placed it on the bike yet. But it is wide. Definitely too wide. But I am not someone who sits off the edge of the seat with a knee down, so if the straps under the seat hold it in place then maybe the edge being cushioned will be for the better.
Although I have already found the best cure for the seat: winter. It is getting too cold and the days too short to be able to go on my weekly 400-mile day trips now!