As far as the fix-a-flat, just take it to a tire place and they can pull it apart it, clean out the fix-a-flat, and fix any leaks for probably 15 to 20 bucks at most.
As far as the ground effects, if you keep bottoming out, you might be able to use inserts or something to raise your spring height. Not sure. run a search on
www.grandamgt.com and you might find something.