I womder if you may be better off with a lightweight 'known' circumference feeder wheel for your wire to run over onto the bobbin. That way, by counting the feeder's rotations, you should be able to reasonably accurately calculate the length of wire fed onto the bobbin, rather than trying to measure 'live' resistance or base it on number of bobbin turns plus account for wire tension, bobbin swell etc. Then, a known resistance per length value calc should be easy to display live.

Not sure if this would be viable though, just spitball'n.