My Turbine builder seemed interested in your idea.
Another thought would be to ride the govenor.
For explanation sake you would lets say have two throttles one would add the fuel and the other would set the govenor
limit.
So you throttle the fuel then you just take the govenor and limit the Rpm via the govenor.
Boat leaves the water it is already on the govenor.
Here is a schmematic of the fuel system taking from the
T53 Work book.
All of the above could be applied mechanical
Via shift cables/Perhaps fabricate a multi stage shift lever
so when applied the throttle would come in and then later
in the mechanical throw the second (Govenor) would
come in and limit the amount of Rpm.
Now that I spewed all that BS Im gonna go watch Mcgiver