The Race Trac is very easy to access, and competitively priced. There aren’t a lot of convenient gas stations right in that vicinity, although there are a few as you head south towards Cocoa Beach. Coming across the Beachline, there really aren’t any convenient stops once you leave Orlando until you get to the Race Trac.
Just my opinion, but I think within 10-15 miles of the return location is more appropriate. 10-15 miles should be ~ 1/2 a gallon of gas or less. 50 miles would be over a gallon.
IMO, leaving the tank just barely on full does nothing but harm the next guest.