Think it should be possible to transfer cave trolls by the means of trains.
How you do that is by taming them and riding them to the train, then clicking the passenger car and then pressing the ride or whatever it is named button.
Or maybe add a new thing called coin on a stick and that would also work. it would be crafted with 1 coin, 1 string and 1 stick
From there your troll will start riding the train, and may even raise their arms when going down steep hills.
To eject them you will need to press “eject troll” and then it will eject them from the train.
This is just an idea of easier transport.