James,
Food for thought from one shop dreamer-builder to another: I saw a YouTube video of a shop tour (Sorry, It was about two years ago and I can't remember who it was.) of someone who had a long bench with two vices mounted, one on each end of the bench and lined up with each other for long parts. If I was copying your build, I might put two removable vices in to do the same.
Me: I have brackets and clamps to add holding for long pieces at the "free" end opposite the vise.
By the way, I have been following your projects and I have to comment that your skills have improved over time and that your designs have become more inventive as time has passed.
Thank You for posting.
--ShopShoe