Okay, based on your drawing above, suggestions:
Increase the aileron chord by an inch
Lighten up the tips. That much 1/4" balsa can be hefty stuff. Four laminations of 1/4" x 1/16" would be lighter and vastly stronger.
Don't get too tied up with traditional kit structures. Some are done like that so they won't break even if the odd spar is a little dodgy/light/has flawed grain and the builder/owner is not really that good at building, but always overpowers his models as everything he owns should be at least scale supersonic.
Andy C designed the Lazy Bee to be really strong structurally, and still be light - as I have proven on many occasions

. Added to which, even the early days 3D Lazy Bees with tuned pipes on racing 21 glows didn't go all that much faster than any other Lazy Bee - the model has stupendous buckets of drag all over it.
Which, bragging again, may explain why I modify the heck out of every kit I build, but all I've ever done over six Lazy Bees is alter the motor mount and servo placement...
D