What you need are big ass fins. The diver size ones that I have are like anchors in a big wind and gentle finning make the Shakey really stable and controllable. At the end of a long day on a big loch you can really motor back to the car too.
The whole tube thing, sitting high or low in the water, is only part of the package. What you have on your feet is just as important and can make or ruin a days fishing. The wee flippers that come with most kits are pretty crap and it is worth spending money on a good set.
And like trimming a boat, weight distribution and bladder inflation pressures also play a part. Too much air and the tube will not sit right, too little and you have no control and you fight the tube. So many variables! But once you get all that sorted, there is nothing finer. The day on Loch Nam Bollocks during last years Highland Fling, might have been fishless but it was the best float tube day as far as control goes. The Red Oktober 2 was perfect, but it took work and a lot of trial and error to get it there.
Nothing finer that a good day in a tube