Now, after testing spalex's model in the simulator, I can verify all what otrcman and BMatthews recommended. The simulator model isn't completely realistic but it shows it's characteristics rather clear.

To begin with performance: For 4.5 lbs weight, use the small 2208/34 motors, with 2s2200 LiPo and 9x6 prop or an equivalent drive with bigger props. The 0.37 thrust/weight ratio gives reasonably scale-like take-off and climb and is well enough, even for grass runways. Less than half throttle is enough for parkflyer-like cruise speed. Landing roll is too short in any case unless you set some power.

Behavior: You just can't avoid tip stall anyway, neither by washout nor by flaps. Both don't hurt, either. I'd pass washout but build flaps because they make for more scale-like (slower than cruise and steeper) landing approaches (much power provided). With or without flaps, no three-point landings are possible due to stall. Just do it the other way.

Don't fret about tip stall, you won't suffer it unless you set out to it. It's easy to avoid having only 10 oz/sqft wing loading. Recommended control throws: aileron 10, elevator 12, rudder 20 (split flaps 60) degrees. If you think that's too little set dual rate to 15/20/30, but you'll see that's even worse. Set 50% (or more) aileron differential and activate 100% aileron-rudder coupling. Roll response is good.

Setup: 0 degrees stab incidence, 3 degrees (or even more) wing incidence, no right or down thrust. That's what the 3-view drawing shows, and it's good. Balance point (C/G) should be 6" behind the center section leading edge (or even more, 7" is not bad, neutral point is at 7.62")).

Great flyer! Still too fast cruise, too small turns, too short landings, too much control response. As otrcman said, it's a compromise. You're on the controls to let it look more scale-like, as BMatthews described. Keep us posted!