This Friday is Off the Grid’s last outing at Fort Mason until the spring, and in honor of Halloween and the close of the food-trucking season, they’re doing a special themed market with a costume contest, and live music from a Rolling Stones cover band. Also, they’ll be celebrating Halloween at Off the Grid North Berkeley on actual Halloween, Wednesday the 31st. And this Sunday, the 28th, is the final of their monthlong series of Sunday Picnics at the Presidio. Organizer Matt Cohen intends to return to the Main Post lawn in the spring and do more picnics through next summer, but for now, you’ve got one more shot. See some photos we took from last week’s if you need any further enticement.