PIano,
I have one similar to those, and I wasn't real happy with it. Because of the seat pan contours, the pad didn't lay quite right in the ****** and I always had issues with it making me more uncomfortable by reducing the circulation in my legs.
I'd be more than happy to send you what I have to try out before you invest in one.
You can likely find a local shop that can customize your seat for you for a reasonable cost.
Another option is to do it yourself. It is fairly easy to remove the stock upholstery, and rebuilding the seat with better materials. Kemmler makes a padding called Air2Gel that is great - http://www.kemmlerproducts.com/ is even is sold in smaller sizes (12x18 inches or 15x18 inches) perfect for bike seats.
Seriously though, your local Wally World may have a mock flex gel pad, similar to that used by Spencer, in a very durable covering with carrying handle for $18. WW's flex gel pad isn't "med" blue.
The bottom is non slip and the top is mess fabric. Just right for a beaming individual such as yourself. I got one for the better half's bony butt. It's a bit broad for the pillion seat.
And now that I've found lovemybubbles.com I'll have to get a matching set of his and her's. I trust they carry wide-load widths. I see they have "nude" and extra padding. Now we're talking; I'm not partial to hot pink.