Phil, wouldn't the control loads be more affected more by the stab/elevator chord ratios than aspect ration?
I don't have WB's articles in front of me, but he had a graph to account for the ratio of stab to elevator chord. I think it was taken from a 50's Navy textbook for pilots. As I remember, the ratio between stab and elevator has little effect on the amount of lift generated. Narrow elevators and wide elevators work nearly the same. The big difference is wide elevators need more control force needed to move the surface.
A second factor is the absolute width of the elevator. From practical experience the last couple years, a 3 in bellcrank can't reliably work an elevator more than 2 in. wide, regardless of the stab/elevator ratio.
My original Giles model used a built up scale tail. The aspect was about 4. The elevators were 50% of the chord, and about 3.5 in. wide. This setup caused no end to control problems. Any speed change resulted in very wide changes in the force needed to move the elevator. It was fine at a 5.1 lap, say, but would start to stiffen up markedly at 5.3.