If trailing width is THE rule framing all comercially designed beach cats, then the "ideal beach cat" needs a new and more user friendly folding system to feature a larger width without sacrificing trailerability. Reducing the dry docking area needed in beaches and clubs also helps.

Note that small cabin multihulls not much bigger then beach cats boomed after different folding systems were developed 20 years ago, notably the Farrier system.

Would a scaled down folding system help? It's hard to imagine a Farrier folding system in a beach cat, but maybe the swing-wing system could be adapted with relative ease. The extra length would not help, though: a folded ARC 30 would result too long for trailing without a permit - but still easier to assemble. Maybe a "swing-float" ARC22?

Anyway, I agree with the "no rules" approach to multihull design. Faster, safer, and cheaper is better. And that's it.