Colyn,

   Not being in a position to see your wing and inspect your contour
asymmetry, I would mark the current position of the strips and then move
them down 1/4 inch and measure the results. Be sure to do the comparisons at
the same weight for a valid comparison. When you achieve a stall increase
that is in the 1-3 kt above the no strip speed, then try strips that are
about 6-7 inches in length at the same location. The position becomes
progressively more critical as the stall speed gets closer to the no strip
stall.
This work will improve your controllability without imposing a
significantly higher stall speed. Depending on your wing contour problem 6
inches should be more than enough to improve the stall and buffet. Keep
accurate records of your configuration and test.

Jack Webb