Adding the tower 56 ping into the equation introduces the possibility of a very curious route to Fusian that night. Here's some
speculation on my part.
By this time, Casey's car is at the Amscot, so she and Tony go to Fusian in his jeep. I say this only to note that they did not drive in separate cars. As they head out, she says to Tony "hey, do you know a back way to get over to North Econ and Blanchard Park without having to go all the way down to Colonial?" Tony says he does, and they drive that route. Casey's motivation for doing this is, of course, to find another route to where she left Caylee rather than having to take the long way.
When they get to North Econ, Casey then says "hey, I have been trying to convince Jesse all day to come to Fusian with us. He's been down the past couple of days and I think it would really cheer him up. Can we swing by his place?" Tony, says "sure" and they head up North Econ to University. As they head up North Econ her cell pings the SW sector of tower 56.
They approach Jesse's and her cell pings the north sector of tower 55. They speak with Jesse, but he's not interested in going, so they head back out. Another ping on the north sector. Heading down Alafaya her cell pings the southeast sector of tower 55. They wait at the light on Colonial, turn left, and then turn right onto Woodbury. On Woodbury her cell pings the southwest sector of tower 44. Approaching Fusian she pings the north sector of tower 38, and then after arriving at at Fusian, her pings are all from the southeast sector of the same tower.
Recall in Tony's interview with LE there was mention of some things they wanted to discuss further but not on tape.
Speculation on my part is that one thing may have been this curious route to Fusian, and another may have been Casey borrowing Tony's jeep on the 19th.