Charles.. Welcome to the site.
Sorry to see you had a hit-n-run issue. That sucks.
The original polyurethane bumbers go like that with age. The slightest touch or temperature change and they split open.
I did my rear bumper cover last year..Doug noted the link above.
I recommend a flexible-fiberglass replacement bumper cover. I hope insurance will cover this damage.
I bought a bumper cover, $500, had it painted, $450, and installed it myself. It would probably be $1500 at a shop. Most bumper covers need bodywork to fit properly. Contact a few local painter for an estimate. Preferably a bodyshop with Corvette experience.
Contact me if you have any questions.
Graham