First off, let some air out of the bladder. It is overinflated if you cannot set the kick-in to 40 PSI. There is nothing wrong with the pump running continuously while you're using water. You just need to find the sweet spot which will depend on what depth the jet has to push the water up from.
Draw water off at the same rate the pump is putting out at a specific pressure and calculate the GPM. Then reduce the flow so that the pump levels out at a higher pressure and measure the GPM again. Do that a few more times, reducing the flow each time and you will have plotted a curve. That curve will tell you how high you can take the pressure.
Why did you not go with a submersible? They are twice as efficient and capable of much more pressure.