No other vstrom seat fits your model, yes the 1000 seat fits a 650 but only the first models like in 2006-8.
Suzuki make a tall seat but as you say it's only 20mm and Seat Concepts make one but you have to fit it yourself.
I also get sore hips and tail bone on my 2014 1000, I've tried 3 seats, footrests lowering kits, airhawks etc and still get it, I hope you have better luck than me!