Neat small glue up jig hairy.
If I read the picture correct those are the Rockler slip knobs you are using.... yes/no, they are brilliant for long threads that are subject to lengthy knob movement... there should be a review (hint, hint) of them here.
Reminds me to post a blog about my small office assembly bench.
If your first cut is too short... Take the second cut from the longer end... LBD