In my experience nature trails aren't good because they don't get much sunlight ("trails" are usually through woods, with trees that block the sun). MJ will die without enough sun. MJ will grow well wherever grasses grow well... typically fields, powerlines, beside relatively wide railroad tracks, etc. In fact, a good thing to look for is whether or not grass is growing well naturally where you're going to put your plant. If it is then you're probably going to be getting enough sunlight there.

You want at least 4-5 hours of sun a day on your plant.... but MJ will take all the sun you can give it. The sun moves about 4 fingers in an hour if you hold your hand one arm's length away from your eyes with your fingers facing you. Use that trick to estimate how much "clear sky" a spot has.

If you're going to grow outside make sure it is in a spot where people don't go often, and if they did go there they would still have a hard time seeing your plants. I also suggest googling "self-watering setup" and doing something to make sure your plants don't need watering too often... that way even if they plants do get busted, you likely won't be there when the cops are. And you won't be leaving a trail every couple of days as you bring water to the plants.