While I'm on this thread, I might as well share the report of the tidal tail of NGC 4438 in my 18" f/4.5
This was from ~5500ft altitude Bortle 2-ish skies near Big Pine, CA but the transparency was poor. In my notes, I wrote down "~70% of the sky is engulfed in haze. Could not give the eyes a second shot but was happy to have called out the location of the brightest segment [of the tidal tail]". The accompanying illustrative sketch I made shows the northern tail of NGC 4438 as a thin streak emanating from the main body of NGC 4438 in the same orientation as its elongation, with a brighter region towards its tip where it ends. The southern tail was not detected. I was using 200x power (10mm Delos).