We've made a few like that before but that usually doesn't involve pan modification. Usually it is simply removing the padding and putting a very thin pad over the OEM plastic. I suppose a guy could cut it down even more if he wanted.
mine is a custom out of calif. it is the only one i know of. but could be easily duplicated. much as what sean said not a long distance or touring seat.
Here's one we did for Jeff's drag bike. Seat actually came off my drag bike and was done back in 1985. might very well be the first cut down vmax seat in the country.
.........or you can get with a local upholsterer and have them cut it down or build it up to your liking with some better & ( more or less ) foam padding & leather to fit you personally.