The Gray Man

I've been looking and looking for a solution to this, but have been drawing a complete blank. I'm wanting to improve the focus on my Skywatcher Skymax 180 Pro - out the box it's just a knob to move the primary mirror (which I guess is standard for catadioptrics?), which is quick but coarse. So what do I mean by "improve"? I mean the following: Provide fine focus control Also provide coarse focus control for significant changes with (e.g.) new eyepiece Do so electrically to avoid shake by touching it Do so with as little extra weight as possible on the back of the scope Do so with as little extra physical space as possible taken up on the back of the scope, or else have it easily removable to store the tube In an ideal world, be able to control that from a PC or Smartphone, but that's just icing on the cake And naturally, do all that at as low a cost as possible! Simple! Yet there just doesn't seem to be a solution ticking those boxes out there for the Skymax 180. I could add a Crayford, but they're either fairly expensive and very heavy, or outrageously expensive and still quite heavy. Other SCTs have the option for something like a JMI Motofocus, but they're not available for the Skymax 180 (and for what they are, they do appear IMHO to be quite pricey anyway). I could put a peanut butter jar lid or clothes peg over the focus knob, which is cheap and would certainly improve fine focus, but doesn't get away from the shaky touch problem. Has anybody found the answer that I'm looking for? Cheers, Ian