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Dean - the simplest way to improve the depth of focus is just to use a barlow lens. An F5 becomes an F10 light cone with a 2X amplifier. Aperture stops deliver a superficially sharper image on nights of poorer seeing. I have never however seen more genuine detail with stopped down aperture than with full aperture. It requires more patience but larger aperture always seems to deliver more. With Jupiter particularly, aperture brings the ability to see colour differentiation in features and even in poor seeing , this colour differentiation allows a whole layer of detail that disappears with smaller aperture ( even if the view is superficially sharper )
Most often I find the culprit when people think their larger scopes are sensitive to the seeing is that the optics are not adequately cooled. If you have an Obsession you are likely to have a 2" thick mirror - which are difficult to work with thermally. If you only have a single fan on the back - fit another two- also fit a boundary layer fan to blow across the face of the mirror and lastly fit a low cost digital thermometer with a probe attached to the mirror.
If your delta between ambient and mirror is not better than 1.5 degrees C you will not have much chance of exploiting what the aperture is capable of delivering. Hope this helps. Often people who fit temp monitoring are shocked to see how much their mirrors can lag behind ambient during the night .
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