” with the two wheels in back are very unstable in turns,”
Ours aren’t.
I tear around mountain curves at 60mph and I barely weigh enough to keep myself on the bike, let alone keep it down any.
We don’t use the typical “independent suspension” rears, though.
They suck and feel squirrely as hell in turns.
[our first prototye was independent...got over *that* bright idea -real- fast]
You have to factor in the rake/trail of the front end for handling abilitity, too.
Most “big companies” that crank them out on the assembly lines don’t.
The factory made jobs I’ve seen are, for the most part, way too short and steep in the front.
My first Sportster trike had a stock neck/triple tree and front end...for a whole week.
Never again.
>My first Sportster trike had a stock neck/triple tree and front end...for a whole week<
Don’t ask me why, but that is funny.
Be safe out there.