In another life I was flying a Baron single pilot finally logging invaluable multi engine time carrying freight.
Our company, impressed with it's payload and speed bought an MU2 but needed a second pilot to warm the right seat for insurance purposes, they offered me this 'position'
Right seat in a single pilot aircraft is as useful as t*ts on a bull, no thanks, I told them then and I would give them the same answer today.
Nothing has changed.