Hi Swarfing, apologies I seem to have ended up critising your design when you didn't ask for help. duh

I just have an inquisitive mind and when I see something different I have to ask just in case they know a special trick

Based on what I have read from other threads I think you might have problems with using deep groove bearings preloaded against AC, but I wont mention anything about that.

with regard to the lock nuts can't you just get 2 more of the wheel nuts and face them down to 4/5mm thick on your lathe?