Tim_B.
TreeHouser
I would be looking for property maintenance/gardening type work to keep the groundsman busy if there was significant demand for this type of tree work (cut n leave). You could use a whistle to call the groundy when needed and have him come to the tree every 30 mins or whatever to check on you-the rest of the time he can clean gutters or pull weeds out.
This kind of situation just begs for the RopeTec communication system. On days when you don't really have enough work for a ground guy to directly assist you in a tree climbing operation, you could add value for the customer as you say, by having your assistant do whatever outside maintenance work the customer desires. The assistant gets a steady paycheck, you get someone who can assist you when needed, and call emergency personnel in a pinch.
The offers to customers to do other types of work that needs doing might actually open up additional revenue streams, depending on the skillsets of the groundies.
You would need to find a ground guy who is humble enough to be game for most any task the customer wants help with. The goal would be to keep the groundie productive and adding enough value so that everybody stays happy. Just a thought.
Tim