Bob Your talking about high and low altitude performance but think about it. Most never ever fly at much more than a variation in elevation of perhaps a few thousand feet, heck some folks never fly anywhere else but their home field. This is not quite like a full scale craft where there are very large changes in altitude every flight

I have done a number of warbirds for pylon racing and have experimented with clipping the wings of some and in every case some may have netted a slight gain in speed but in every case they became far more of a challenge to land.

So when you say "landing is terribly difficult for me" reducing wing area, increasing wing loading and increasing approach and landing speeds by clipping wings is a poor choice.

I like j.dunckers suggestion of a TA-152.

John