Is parking along a designated route considered “off-trail”?
No. As a general rule, park as close to the route as you can without blocking the trail, if you cannot find a wide spot that is appropriate to stop at. Please don’t park on fragile vegetation (cryptobiotic soils, alpine tundra, etc) and don’t run over trees and shrubs to find a spot to park. Many ranger districts are directing enthusiasts to stay within one vehicle length of the route. The same standards should be followed when recreating on BLM lands.