Mountainous/hilly/rocky/trench locations are good if you need privacy.

Also, maybe one of your homes has a sizeable backyard with a hidden part. Keep your eye on the back door and make the sessions brief. Beware of neighbors.

Back when I had to smoke secretly, before moving out on my own, I was pretty good at "smoking in installments" while going in and out of my parents' backyard during evenings.