Long drive day, indeed. That's about 7 hours' driving, leaving almost no time to stop and enjoy the lovely places en route. Don't underestimate the toll of driving those narrow, winding, remote roads, and on the "wrong" (for you) side of the road, too: it will require constant concentration and will be exhausting. And then you're going to do it all again, but to Glasgow, two days later.

Skye is really not feasible as a side-trip from Edinburgh and, as beautiful as it is, I think you'd have a much better vacation if you dropped it from your itinerary.