This is a 15 ft. cat with a separate frame (simple rectangle of tubing) at the front, rigged to all four forward d-rings and strapped to the main frame with standard 1-footers. It's sized for two York Packs (plastic dryboxes) that ride high and help ramp up on waves.
The rear bay (with cooler/passenger seat) is a rigid part of the main frame, with no dropsó the cooler hangs on 1.5" straps. So the frame rides handily on a roof rack (on a Honda CRV), and lets you open the back hatch.
(The two grids at the side are dog decks.)
Paco (Jack's Plastic Welding) recommends running his tubes pretty tight, so there's not a great deal of flex unless you hit something huge (or a boulder). But one thing to consider, particularly if you tend to let tubes go soft, is the chance that a two or three-part frame like this might taco, i.e. fold up and mash anything in the way. (Given the floor area, a raft is more likely to taco in big water than a cat.)
If you do go with this set-up, make sure that you don't put your passengers at risk.
But I've used this for years and am happy with it.