Not sure what other vital information I'm with holding
Well there is:-
I just don't have spare pins
want to stick to using the analog input
that encoders needs to be reset every time to find reference
still expensive in time spend building and setting it up
All would have been good to know at the start.
You can use an op amp to add an offset voltage and a reduced Vref. However, that means you need a negative voltage rail so I suppose that rules it out. If not look up "op amps DC offset level shift" for the simple circuits.