I used the single fork arm 8SE too. First I centre with my reticle 12mm EP.
Then I use the maximum resolution in my imager (NexImage 5), and ideally have that pre-focussed (try to mark a point on your focusser). Also turn the gain right up.
Doing this I had no problem getting Mars in the FOV at f/10, and a moderately easy job at finding it at f/25. You can turn the gain/rez back once it's centred. Oh, and turn your imager such that left is left and top is top on your HC - makes life much easier
