Wild boars usually do not roam alone, I have seen them in groups of 8-12 in the aegean Turkey. They almost certainly come at night, sometimes even day time. Day times are not much problem. About boar trails, they do use human hiking trails as theirs. So you might not see a trail around you if you don't roam around and inspect. In the area I camped, there were several boar groups (most likely families), only 1 of the group was charging to the tents, not others. It seems certain group psychology is working here. Do not leave any kind of food in the tent, put it in the car when you're done eating. Do not litter your food or dispose parts of your veggies around (not even mentioning meat, duh). It is best, if you keep your trash in the car (I know stinks, tie the bag tightly and dispose first thing in the morning). Do not use your flashlight on them. Dogs really go wild for boars, so if you're travelling with dogs, it is almost certain that s/he's gonna bark, you have to block this behavior. Boars dig and find their food, so do not bury your organic waste, this will make them come and dig, which makes noise in the night, and make you feel uneasy inside the tent. Look to the trees, check if there are boar hair on them, they usually rub and leave their smell, likely later another one will come to smell, and probably rub (same with bears). If they come when you're outside the tent, do not run or make sudden moves, move slowly and act you're not interested with the boar (this is quite difficult if you're with a dog, handle your dog), pepper spray or that kind of spraying would do almost nothing to a boar, you'd make situation worse, do not attempt pepper spraying, remember you are a 'no-threat'. If you're with a dog, make your dog sleep with harness, and never go out at night without a leash.