The Crooked River Forest consists of five parcels all together. Two of them (as of 2019) have trails: this one and Intervale Preserve, in Harrison.
Twin Bridges has a parking area, kiosk, and a system of pathways, which were being constructed in the spring of 2019 (which is why my map is incomplete). The river—a major tributary to Sebago Lake— is lovely, and makes for pretty spots along your walk.
Directions: The trailhead is off Route 17, just about 100 yards of so from the rest stop.