I like the raised stays idea. Makes for easy work....except negated by what looks like nightmarish cable routing!
would be interesting to see what mounting points there are, looks like a bit of a wanker to strap anything to it. Pretty sure you'll have to buy their own shit.
Douze Cycles is releasing a new cargo bike in 2023.
Douze Heta. Looks similar to the R&M Packster if you squint.
https://www.weelz.fr/fr/exclu-douze-heta-la-marque-nous-devoile-son-nouveau-velo-cargo/galerie/