I have an EdgeHD 8 with a MoonLite focuser and (sometimes) a 0.7x reducer.
For planetary, I don't use the 0.7x reducer, and I use a 2.5x Televue Powermate to give a 5,080mm FL.
What happens to the backfocus? I recall adding a bunch of extension tubes once, but is there a less random way of setting the spacing? Or even better: knowing what it should be to save time in the field?