SwiftPaws is designed to run on level ground. The possibility of setting up on a hillside depends on the degree of incline. If the hill is too steep, it may not be suitable to set up and run a SwiftPaws course. One way to determine what "too steep" is to try it. It may take some trial and error to determine what works best.
When setting up on uneven terrain or on a slope, the important thing to is to try to keep the line at an even distance from the ground (not dragging over a hill or rising up off the ground too far). Strategic placement of the pulleys will help. Place the pulleys on high and low spots to prevent the line from dragging.
Image inclines are exaggerated for illustration purposes and are not meant to be representative of actual degrees of hills and uneven ground.