That's probably a good strategy, with the carabiner. I'm wondering about tying a double overhand or barrel knot as a stopper, leaving a long tag end, then burying the tag end in a locked brummel to hold the knot. Not sure if you could make the brummel if you already have a brummel loop spliced in the other end, but it seems like you probably could. Might need to stop the "full length bury" from the fixed loop end a little bit short of the stopper knot end, to allow you to make the splice and bury the tag end from your stopper knot.