I must say, installing any datewheel overlay is a pain in the but, The overlay has aling precisely with the actual datewheeel, it takes a lot of patience and perseverance. keep trying and trying until is right. I myself has gone pass that experience with UBI's datewheel. I manage to install the datewheel on top of the original eta datewheel, used baby powder to remove the sticky on the back after installing the datewheel.
If you do not want to use a thicker dial spacer try to not to tight movement too much with the clamps. that will allow some free movement between the datewheel and the dial. I wish I have a thicker spacer but i do not have one.
Anyway here are the pictures, comments are welcome.