What would pulling 500lbs give you that continuing to lift would not give you? By the sound of it you could shorten your overall lifting career by continuing to load that lower back. You are not the only powerlifter who has had back issues. Look at Vinnie Dizenzo. He is a bench only competitor because he ruptured two lumbar discs:
Vincent Dizenzo - Powerlifter/Bench Press Specialist
His bench at that time was his weakest lift. He dedicated himself to it and has now benched 600lbs in two weightclasses and is working towards his third.
I guess what I'm saying is take emotion out of this and think sensibly. I have no doubt that you will get more out of continuing to lift and compete in bench only and saving light work for lower body stuff. Maybe get into a shirt, single ply, double ply, multi ply. Look into it. Benching 500 is way more impressive than pulling it anyways