You're in good company....
Also wouldn’t mind a small Mossberg Shockwave right now too either. Another shoulda bought it when I had the chance opportunity missed.
What to do? Decisions, decisions, decisions.
My brother badly wants a Shockwave; even offered me serious money for mine.
(Which I hardly ever shoot. But I'm going to keep it.)
Best I can do for a "backpack" gun right now is either the Tavor or one of my 9mm Glocks outfitted with the 33 round magazine. Both of which would be oddly oversized / disproportioned to the concept of a backpack gun.