RE: Shortened Slow Stick
I don't have that exact plane, but from experience I can tell you that is generally a safe bet to have the CG about 1/3 of the way in from the leading edge as a starting point. Try to fly it in no wind to figure out its behavior easily, as well as if you're just learning to fly.
When flying, if it wants to nose up too much/easily, move the wing back about 1/4 to 1/2 inch to move the CG forward. Or if it wants to nose down too easily, move the wing forward to adjust the CG rearward and keep the nose level.
Of course, how it stays level depends on how fast its flying, in addition to the elevator's trim and CG combined. I can set my Slo-V (similar plane) to fly at 40% throttle so that it's level hands-off, and noses upward under more power. Or I can set it to be nose heavy so that it doesn't keep pitching upward into the wind, but then I need to hold some elevator to keep from nosing down, and/or higher speed in order to stay level.