I have a homemade bespoke collective which clips onto a TMWH and with a little stabilisation adaption works the very best - I have had thousands of hours on this and it owes me nothing.

The Collective head has a multiple of HATS and switches and a twist grip throttle with hall sensors all into a arduino board with a usb lead.

Use with a TMWH or adapt to a pivot and a hall sensor via another arduino board - simple enough to do...

Whatever, it is available for postage and a bottle of Italian or Spanish wine (note... no french ha ha) if anyone can use it else it stays in the spares box...