I’m a victim of loose bearings (on 8" hubs), too. I can feel your pain
For this issue I use kapton tape which is only 0.04mm thick. If the bearing has play all around the bearing in the hub start with one layer of kapton tape (no overlay), if needed add a second. In my case it’s almost on 2 sides only so I’m adding shorter stripes. This works also great on keys which wiggle in the keyway of the shaft or pulley. Kapton tape for the win! But it is important to have it almost pressfit, otherwise the tape will move later.
This is what I did on some hubs but don’t file too much. Insert the bearings and spacer first and press them together with thumb and trigger finger. Then try to push and pull with this hand to see if the bearing moves sideways. If this is the case then the spacer is too long. If the spacer is too short you would squeeze (harm) the bearings when overtighten the nut.