CarexOverdoor Cervical Neck Traction Device - Back Stretcher Spinal Decompression and Neck Stretcher Device for Over The Door

Does the door need to be solid?

My main issue is a sore jaw, wondering if a mouth piece may help?

Does the Velcro fasten in front? Or in back?

Does this have a strap that goes around behind the head? And as a single living alone, would I be able to get into it without help?