Here is a new alternative method to mount the MakerSlide V wheels. These are eccentric nuts rather than spacers. They can be used to mount wheels very close to the plate. The closer you are to the plate, the stiffer the carriage assembly is. They are intended to be mounted on the back side of the carriage rather than as a spacer, but they can still be used as a spacer/nut if you like. The nut is thread for a 5mm x 0.8 screw.
Here is a wheel mounted only 1mm away from the carriage using a shim washer.
Here is the drawing.
I will put some in the store real soon.