Here is the design problem with spacers...
1.) The center-line (plane) of the wheel should go through the center of the wheel bearing. This distributes the load through both rows of balls. This puts the least load on the bearings... Think of it like skiing. When you have equal loading on both skis, you go much faster. Through a turn, you do slow down. That offset (wheel spacer) acts like a crowbar and puts unequal and a significant moment on that bearing.
Are the bearings strong enough to take it? YES! Is it a good idea to constantly "up"-load the bearings? Hell NO!
2.) Your studs are 12-mm in diameter. It is OK to space them up to 1 diameter...12-mm thick. After that, you need studs in the spacers and bolt the spacer to the hub... two problems with that. Weight first...you are not adding lightness per the Lotus way. And second, most manufacturers use recycled aluminum for those spacers and the studs strip out! Your lug nut spins with the stud and can't get your wheel off! That is fun!
Wheel spacers are NEVER a good idea! Don't ghetto-ise your car...