If I were to game Gasparilla by the way, I would: for the 15K -- run till the 7.5 K mat and then stop and cut the median and run back the other way after some injury faking. That would lop off well over a mile. There are no other mats. No one would notice or care.
For the 5K, I would run the first 1/2 mile where you then pop out onto Bayshore, and then stop, get injured, cross the median and then start walking the other way back to the finish, blending in with the 15K walkers/stragglers who are coming in 2.5hrs after the start of the 15K. Simple.
I don't know the marathon setup.