Quick fix for sagging Acorn Boxy Bag - Corrugated Plastic Stiffener

Quick fix for sagging Acorn Boxy Bag: I had found that the front pocket of my Boxy Bag was pulling down on the front of the map sleeve/bag top and making it sag in the middle:



So I cut an appropriately sized rectangle out of corrugated plastic ("stratocore"), covered the edges with gaffer's tape (reinforced electrical tape) so that the sharp edges of the plastic would not abrade the bag, and inserted into the front pocket behind my spare tube and tools:



And thus, the bag substantially holds its shape now. As an added bonus, if I ever need some tape for a roadside fix, I could peel the gaffer's tape off the stiffener and reuse it. With stiffener in place: