Yesterday we had a transit of the GRS nearly at the meridian. I observed the spot with my 4 inch refractor (only the spot).
Jupiter is rather low here in Germany, at meridian only 23°. The spot could be detect easily, but the details in and around it were much harder. Nevertheless, I could glimpse at least a hint of the edy trail. My friend Robert saw around the same thing, with only 63 mm aperture. That means, first we need a combination of the planet higher in the sky and a more steady air. Aperture does not help every time.