I initially thought LE was saying a vehicle was parked at CPS from noon to 5pm, that entire time, which I thought was weird. For me, it was hard to come up with a scenario with that car/truck/van sitting there all afternoon and, like you, I couldn’t fathom the killer walking the length of the trails in the open after killing two girls and risking being seen.
Now I think LE meant that a vehicle was parked there at some time between noon and 5pm. Another example of LE maybe putting out poorly worded information. Maybe the killer’s vehicle was only there 5 minutes or 20 minutes between those times.
Anyway, my thoughts now are that the killer pulled into the CPS parking lot sometime between noon and 5pm. Stayed a short period of time…doing something, maybe considering parking there but changing his mind, maybe stashing a phone he knew not to take with him…then left and parked either at the cemetery or farther down at Wilson’s Bridge.
Just my thoughts.