Consider this a lesson learned. Suck it up and live with it. The last thing you want to do is make another brash decision and trade it in at a huge loss.
The biggest move I would recommend is putting it out there for a possible trade with cash on top for a used Z. There are quite a few members on here who are looking to switch to a 5.0. Other than that it seems you already have a plan in mind to go for the next generation Z. Stick with it. The last time you deviated from your plan you ended up with a mustang.
Measure twice, cut once. Words to live by.