Mike C has used 1A rated current regulators for his drivers HERE. He isn’t really talking much about his driver design. But, if you PM him, he would probably tell you what those regulators are and where to source them, and maybe how they connect in the circuit. That should save you a lot of space compared to AMC7135 regulators.
A quick search online tells me there is a type of FET that is “normally closed” and is called Depletion Mode whereas the most commonly used FETs are typically “normally open” and are called Enhanced Mode FET. I don’t know how that works, other than the obvious implication that it will “conduct” when it is at zero volts and then when voltage is applied it stops “conducting”.