The only way to do this is to move the walls! or crack some concrete and move the pipes. Or, leave it where it is. With a clamping drain, you'll either be building another conventional shower, or use a conversion drain and switch to something like Kerdi. Or, if you do end up moving it, just a drain for the system you choose. While it is nice to have the drain centered, it doesn't have to be - it must means the slope on the shorter wall will end up steeper (if you do it the way most people recommend it and have a level perimeter).