As befitted a research establishment the RAE were not looking to mod the Harrier fleet but to start with a clean sheet of paper about what the pilot should be given in any Harrier replacement which turned out to be the F35B. I won’t bore you with the very large number of “what does the left hand do and what does the right hand do” ideas during a whole raft of possible STOVL manoeuvres, however we flew most of these options in the VAAC Harrier from the completely digital rear cockpit, the front cockpit having normal Harrier controls for the safety pilot.
Out of interest, why not mod the Harrier fleet? Perhaps it's a bit late now but there must have been a time when it would have been useful.