My mate and I have SK1's.
He had his seat done by
http://www.motorbike-seats.co.uk/ in Coventry. They're a father and son outfit, decent folk, and they do know about bike seats. Talk to them and they'll do exactly what you want, true custom.
Mate had his lowered slightly (top surface is now curved instead of flat), a gel pad fitted, and a new basket-weave cover. It's well done but rather expensive for what you get (£90 odd).
I did mine myself, followed the same shape as my mate's, but without the gel. It's way way better than before, and I'd recommend the re-shaping route will probably give you 90% of the benefit without having to go to a gel pad. It's perfectly do-able as DIY if you're that way inclined, all you really need is a decent staple gun (Arrow or similar, around £15 or 20) to refit the cover.