Switched back to 8.5 from 8.38 board and had a new set of ace 44s to try, too narrow. Went to the shop got some 55s, too wide.... I had that bushing dilemma as well.... So far my quest to start riding aces is on standby...
As said, three washers on the inside only - don't need anything on the outside as the wheel nut almost have their own built in washer nowdays.
This is how I have run my setups for a long time and although sometimes the wheel doesn't seat the bearings correctly, I almost never have issues with length of axle and 3 washers, but I have a ton of spares, some wider, some thinner, so I can mix and match a bit too if needed.
Thinner washers only even fit four on some trucks, but as long as the wheel nut is firmly on (not able to be turned just by your fingers) you should never have issues with the wheel nuts falling off.
It really does make a big difference in where the wheels sit and don't be alarmed by seeing a lot of washers when you look at your wheels (if you ride thinner wheels, that is) but most of my normal size bigger wheels cover them nicely anyway.