I thought i read somewhere you wanted 20mm spacers. These are available in the hub centric spacers i'd imagine, quite readily available. The reason extended studs are a bad idea is the load placed on them is further away from the hub which means more forces.

Also looking at the pictures above, it looks like there is plenty of thread left on the current wheel bolts. Are the spacers just for a 'stance' thing or because the wheels don't clear your brakes without the need for spacers?