Having lived in Dublin Tx for 2 months of rotations. . . Stephenville/Tarleton State being FBS just seems like your stretching too far.
The schools is not really that big, the supporting town is not big either.
Many of the students don't stay on campus, but leave on the weekend to go home or go up to DFW to party with friends, leaving a pretty lackluster social life on campus.
Their stadium holds 24K and unlike when I was there and the game had 5,000 people tops. .. Apparently they are filling out their stadium. So this is good enough for a CUSA or MAC like school.
Overall, just seems like Tarleton State would lack the resources to compete at the FBS level. But I could be wrong.