I'm not sure what a mini-SUV is, but 5 people would be a little tight in even many mid-sized SUVs. I'd go with a full-size sedan or a standard-size SUV.
Allow extra time. I once stayed in Orlando that week and worked in Sanford (this was back before Sanford had hotels worth staying in...) Every day I-4 got more and more congested and by Thursday what was a 15 minute drive took 30 to 40 minutes....
Remember that what you consider a "full size" and what the rental car company considers a "full size" may not be comparable. Check out their car selections first.
That's going to be tight. We had 4 people in a full size one time and couldn't not fit all the luggage in the trunk, one piece had to cram in the back seat. Full size is a Chevy Impala or Toyota Camry size.