You are 100% on the bummer of long clamps on short jobs. Sure you can notch some 2x wood to make intermediate supports, but that means cutting up valuable 2x4s that I've been hoarding.
I've been looking for replacement handle ends since my screws are buggered from over tightening, but you bring up a feature I have used in the past.
The second? generation has the hole at the end for the clip-on support which helps, but is still at the wrong end.
I'll slide the handle end off the bar and then slide on (backwards) a handle from another clamp, followed by the original end, making a two clamping jaw clamp much like the setup you created.
I'm too squemish to pop my rivets so i'll work in a pinch.