It's going to be tight. It is about a 45-minute to an hour drive to Orlando on a good day. The time it takes to get and return the rental car will delay you even further. And don't forget about airport check-in and security.
Additionally, while the ship docks at 7:00 am, it will most likely be at least 2 hours until the first passengers disembark. Depending on the criteria used, you might not be in this first group.
I have two suggestions. The first is to hire a private car service to meet your party at the pier and drive you directly to the airport. Several shuttle services offer these -- they cost a bit extra than a shared van, but are worth every penny in my experience.
I also suggest that you pack in a way that will enable you to carry all of your bags off the ship yourself. Carnival has a policy that those who don't check luggage the final night can disembark first. I'll have to verify that this is available in Port Canaveral, yet it will get you off the ship sooner. Of course, this won't mean that you will be the first passengers off the ship as many others will have the same idea, but it may get you off more quickly.