Tying the rear frame rails together? Opinions please!!!

Any structure you add to the car will help. It isn't just about about handling and preventing twist on acceleration. It will also increase your odds in the event of a wreck. I don't want to install a cage in a driver, but I want to have a better chance in case someone decides to impale their car onto mine. It seems to me that there isn't much structure preventing the rails from moving inward due to a hit anywhere on the side. I realize the doors and the b-pillar will fold quickly, but more bracing might be the difference between life and death.