I know theres some short 5th wheels but we didnt find many/any under 28'. We started with a 28' Rockwood because it was the lightest pin weight we would find at around 1100#. However with that being said it towed poorly on our F150 eco. Also any pin weight you get from the manufacturer I would view as the best case scenario empty. Most are over the advertised weights, some by quite a bit.
You don’t say how old you want to go, but a early 2000s Sunnybrook 27 is a great rig. It uses a full aluminum superstructure, not laminated walls.
We had a Sunnybrook 27RKFS as our “starter” 5th wheel (we had bumper pull units for about 30 years) in 2017 - 2018. We did that so we could determine what we did and did not want in our “retirement” 5er. Empty weight is in the upper 7000 pound range with GVW in the 9000 pound range. Super-slide (dining table and sofa) in the living area.