The easiest would be to book a rental with a drop off near Universal. Avis has a desk in Universal hotels. Other agencies have a location in walking distance. Uber rates from MCO to Universal have been over $50, not all the time. Enough for me to book a car service. Are you willing to wait at MCO, hoping dynamic pricing will reduce the fare.
Dropping the car off at MCO might cost you 90 minutes and $50.