Average returns and square of the std dev of returns can be used to derive scaling factor. Volatility needs to be a factor. It is unrealistic to do this manually every time you decide to scale in. I am not sure inverse will make an ideal hedge. Why are you not considering option to hedge. If you are in and out fast it is hard to work a hedge. Someone like Destriero may have a better guideline without infringing on their edge. I am not sure this thread has gotten his attention.
You are right, Kelly is typically a fraction of your total capital (perhaps 5-10%?). If you scaled in so that your total bet in this one trade is > 5-10% you exceeded your Kelly. Maybe I don't understand Kelly. If so correct me please.