If you are looking for more work, ask for am shifts and if the driver is finished with you, call in to the center and let them know you are willing to work with another driver if they need you. BUT, make sure you work your way up to this because you could burn yourself out if your muscles aren't up to the workout. Make sure you stay hydrated, keep up your caloric intake and wear sturdy, comfortable footwear that will support your arches. Sprained ankles gets a lot of helpers. Make sure you use clear pathways and don't take shortcuts through grass and shrubbery that can hide obstacles ...especially at night.
Have a great peak season!