If you're taking DME, why aren't you checking most of the luggage thru? DME will deliver them right to your villa. Even with a checked baggage fee, it will probably be more affordable than renting a car and car seat for the toddler.
Groceries can be delivered to your villa by luggage services if they arrive at SSR before you or you can have them delivered right to the villa after you have your room assignment. Of course, you will need to be in the villa to accept the delivery. ETA:
Walmart will deliver directly to your villa.
That leaves the same carry on bags that you had to deal with at the airports. Are you bringing a stroller? Load some of the carry on luggage in it and allow the little one to stretch their legs a bit once you arrive at SSR.