I've been designing a test bench for RC propulsion systems and for that I thought it would be nice to be able to switch the power to the ESC on/off. For this I designed a simple circuit which I thought would do the trick. Vaa is used for both driving the gate and the ESC. However, as it turns out, the ESC GND is internally connected to the GND of its servo connection. First this means that the ESC never turns off. Second, this is quite dangerous when the MOSFET source isn't pulled to GND (open switch)! In that case if someone was to open throttle, the current would most likely kill the flight controller instantly. Another downside is that it is only possible to use/simulate a 3S or 4S battery pack (maybe 2s but not optimal) since Vgs of the MOSFET can't go above 20V (5s is 21V when fully loaded).
I think I've come up with a solution to both these problems by switching in the high side of the ESC and using an isolated DC/DC converter to drive the gate. The converter converts a 5V signal to a 12V signal which is high enough for the Rds(on) to be low enough to support a current draw up to 40 Amps with appropriate cooling (6 W/mK thermal pad and 2.7 K/W heatsink). However, I'm not sure this setup will work as I've never worked with such a converter before.
My question is basically if there is an obvious mistake I've made and what this mistake might be. Also if you have any tips as to how this circuit might be improved you are more than welcome to give them!
PS: This is my first ever post on this website. Feel free to comment on the contents of my question and how I might improve future questions!