I have a set 21 inch diameter and 28 pitch 6 blade rolla cleavers with a 25 spline hub ( Arneson ASD8) not sure what sort spline trimax is using.
You could take some diameter off these props by a propellor shop.
I need 3000 € for both ,these are almost 6000€ each I,ve been told.
This is just a tip, but over att Boatlife.se, there is a guy called 38KV...PM him, he has som Rolla-stuff, not sure about what though, but might be worth a shot.