Hey Phil, Spectacular job! One of my fave's, great idea, you done good! You've got some talent with that airbrush too...
If the wing is lifting up-wind consistently, you probably have not added enough tip weight other than to just get the wings to level. Sometimes it takes a little more than "just enough" to counter act that.
Also, I would venture to say that getting the wings level with dihedral is probably a tricky proposition to see for the casual observer. You need someone with really good vision to sight down the lines while you fly to see if they follow through tip to tip at various altitudes and attitudes.
Lastly, I'd make sure you verify your actual laps speeds are the same for each trim session and I imagine between 5.0 to 5.2 or so would be good with a plane that size. I say this for multiple reasons... but mainly so that you have a steady base-line to watch your trim changes take effect.
Hope that helps,
EricV