11 week puppy (understandably) cannot be left alone. How do single dog parents do it all?

Hi! I have a lovely 11 week old puppy. I completely understand why he cannot be left alone for more than 10 seconds, as he's only been home for 3.5 weeks. He starts barking and screaming his head off. He is very happy in his crate at all times (goes in there on his own to nap, sleeps through the night in there), but 10 seconds after leaving, he starts panicking. I am working on separation training and always feed him in there, etc, but 1-2x a week, I have to leave from 20-60 min at a time.

I am a single dog parent — this past weekend, I had to leave for work for 2 hours, and I felt so bad, because my puppy barked and cried the entire time, and undid all his hard separation training (prior to that day, he could be left alone for 20 min and put himself down for a nap). Now, he panics after 10 seconds. I am scared to keep undoing all our training the 1-2x per week when I have to leave for longer. I tried covering the crate, which doesn't really help him. I play with him a TON and keep him awake for 2-3 hours before having to leave for longer. I also put him in his crate for a nap and ignore him for 15 min before leaving – but my door is loud and he usually wakes up when the front door shuts and understands I've left.

How do I continue training when my outings 1-2x per week undo our training? It's like 1 step forward, 2 steps back. Do I need to hire someone to sit with him?

Thanks!