Wife and I thought we'd share the following...we spent an afternoon some time ago and got the dimensions from our local DMV Motorcycle Test Course. We then painted same at an abandoned parking lot near our home. Perhaps you can do to same...I've used it, my wife, two of my son's friends and whomever goes up there to practice. We opted to paint by brush and now have access to a paint striper unit that we can borrow...will need to be touched up soon.
We still go up there to practice...we've added a dead stop 90 degree turn (U-turn) to our drills.