Yes the wire channels are huge on these GLS locking connectors.
What you suggested is exactly what I did the first time. I cut about 2 1/2” extra insulation off and double bent it on itself. At first tighten down I thought it was enough. But I guess the inserting and pulling out when I was swapping between the 14 gauge to listen must have worked the set screws loose. I literally pulled the wire out the connector without too much force when I inspected it. They are all like this sadly. The 10 gauge is not thick enough and the set screws are not long enough. They literally screw out into the channel.
Don’t want to buy another set of locking connectors yet so I may try soldering the wire in the channel. But first I’ll try a triple bend it and see if that will hold snug. I would prefer to keep it a more easily removable connector instead of soldering it in.