I suspect that barring some other issues with the PO as long as he is home at night, servicing jobs at a distance isn't going to be a problem. If he's talking about more than that, then he'd need to make a good case to the officer.
They only have to go through the interstate compact (getting the other state to approve) if they want the foreign state to perform the supervisory role. If the Commonwealth wants to keep doing it, they don't need anybody else's permisison even if the guy up and moves to another state.
It usually boils down to what the PO sees as a risk. Some probationers are required to get a travel permit for each trip BEFORE they go anywhere. Some are allowed to just drop a notification by phone. Others get a blanket auth from their PO.