when you have it apart for tires you could swap on your old XJ/zj 6cyl coils unless they are sagged to hell they are actually 146lb/in vs your stock LJ coils which are 134lb/in another option would be v8ZJ coils which are 158lb/in which would give you about 2" of lift to level it out.
After 3 days I finally got the sides stretched enough to get the back window zipped all the way. I'm going to return the Instatrunk. It wasn't what I expected so I ordered a 30 x 14 x 16 underbody truck box instead. It will work like the Instatrunk (accessed from the tailgate), but is bigger and sealed.