RE: Raising stall speed?
I think this can be achieved aerodynamically. Not just by adding weight. (albeit wing loading is aerodynamics, I know) I have had plenty of very lightly loaded aircraft that did not act this way.
This is also not my plane. They are beginners, and clipping wings, or doing any structural mods is not really an option. Unfortunately, most newbies don't build anymore, so I doubt they have a shop let alone the skills to do any serious modifications.
I was kind of hoping I could turn a clevis or shim the wing mount. There are so many trainers out there and it is too bad that some of the great classics could not be more prevelant at the field, like the Sig Kadets and such that are proven designs that work.