I don't think spring poles are an unsupervised play option. There are too many what ifs. And attaching it to an actual wall stud or the actual door frame would be much safer. Once your dog is comfortable with pulling, that pull up bar won't stay up long. My dog is a very lazy dog that puts out no exertion in life, but he can still pull me across the floor and I'm a fat kid at 230 lbs. They key to leaving a dog home alone that has high anxiety is to tire her out BEFORE you leave. Very long walks, flirt pole, treadmill, spring pole.
"i can explain it to you, but i can't understand it for you."