First I'm taking them to the cobbler to see if they can add some padding and stitch that part back into place.
The rivet where the cuff screw goes was tore off as well, so I'll either need to find someone who can add a new rivet there, or drill a new hole myself.
I don't know how they'll perform, but I think it's best to try and salvage them before buying a new pair.
While this boot is out of commission, I've been using a different setup on each foot: 4x100 (like the one from the picture) on one, and 4x84 on the other, with different boots and frames. It's not as bad as I thought.