Which way does the the chainline need to move? That is, which way is it out of line? Sprocke inboard of chainring or vice versa? The spacer method will allow you to move the sprocket more toward the non drive side, ie sprocket more inboard. Moving the axle back and forth doesn't seem like it would do anything. The hub will still be in the same position relative to the dropouts. Are you using a true single crank or a double crank with one chainring? If a double, do you have the chainring on the outside or inside of the spider? I put mine on the inside of a double crank and got a pretty straight chainline even with a 113 mm bb spindle. What about the bb? Was this bike originally a road bike set up for double cranks? If so your bb spindle may be too long.

If I could see your setup I might have some ideas. Hope some of this helps.