If you own a tap and die set! You can cut them down. You need to grip the center bar with a wrench if ou can see a nut, or needle nose vise grips if no nut. Then twist off the top cap. Be careful because it's obviously under some tension. Then cut your springs from 1-3" off. Whatever you cut off, also cut off the center bar. Then re tap the center bar and thread the cap back on. Boom, shorter shocks one the cheap and right way.
Also, if you cut slightly more off the bar than you did off the springs, you'll have more tension, so more 'per load' and less chance of bottoming out.