Hello Bruno and Welcome,
I am planning to start constructring a working flevotrike able to carry 250 kg. Jürgen, told me, Gavin Katts has constructed something which could be a model for me. Gevin, wo bis du ? où es tu ? if you read my message,
The Triton made by Gavin Katts (South Africa) seems like a good solution for carrying heavy loads. It is convertible from the trike to the bike version, in case you don't need the trailer. As Gavin is still subscribed to the list he might give us some more info on his bike.
Also interesting is the trike, made by Mark Schaaf (Germany). Au Revoir, Jürgen.