Didn't see what kind of trainer you're flying -

The only real limitation on what you can / should try is really wing strength. Given that it's properly built and doesn't have hidden damage, most anything that starts from from level flight (upright or inverted) should be fine. I *would* stay away from full-power dives followed by hard pullups though.

If it's a flat -bottom wing it'll respond well to reducing the wing incidence by putting a shim under the trailing edge. For an LT-40, 3/8" isn't excessive. You should find then that you need to adjust the elevator trim a bit, but it should be much nicer in the air.

Rick