I took my seat to an auto upholstery shop. I had them trim about 2" off the back, tapering to 0" about half way to the front. Made the seat much flatter, and no more scooting forward.
My wife made a cover for some foam seat padding, and I strapped it on top. Way more comfortable now.
Here's a link to my KLR page. Scroll down about 4 images to the section on the seat mod.
2017 Yamaha XT250
1990 Honda NX250 (Green/White)
2011 Kawasaki KLR 650 (Orange & White )
My KLR Page..http://www.powers31.info/2011_KLR650.htm
Mod's to KLR:
Power socket, L.E.D. Battery Indicator, Camera bag holder
Custom Saddlebag frames .
Louder horns, Firstgear Onyx tail bag.
Custom Aluminum Skid Plate.
Cut down seat with Custom pad.
Go Pro Camera mount.