Use superglue to glue the washers to the bearing. I used gel version, because it allows slight adjustment to better center the washer with the bearing.

It took less than 5 minutes to complete the thing. It is heavy, but not too bad. So far, with relatively small usage they seem to be working fine, will see about it when it gets more usage.

One thing I noticed: if you put M8 washer so it is inside the M16 opening, depending on manufacturing tolerances and centering of M8/16 washers on the rod/bearing, it may have sometimes chance of catching. I had this happen once. If that happens, just try different washer, file/sand it smaller, or center it before tightening the nut. Using nut directly against the bearing seems to work very well though. On the last assembly, I used few passes with round file to make the M16 a bit bigger inside just in case.