Never used a sprayer as a paint marking device. I am a five gallon bucket guy with a grid rack you see used in construction and a 6 inch roller.
Get the lousiest pair of holy jeans and worthless tennis shoes. Go to walking and painting. Depending on the property boundaries, it will get done. Main thing is to get it mark extremely well so that five years down the road the trees still show the paint.
Parking lot blue with an oil base is what I used. Concentrate on eye level.
Toss clothes when finished.