Mine fires like a steel bear trap. I honestly don't trust the assembly not to damage itself so it's become second nature to ride the pedal home with my foot every time I start the truck.
I've done a fair amount of wheeling on inclines and never needed to use the parking brake the way OP is proposing but... if you really needed the assist, couldn't you just lock the parking brake at like 25% so it drags slightly, apply enough torque to get yourself moving, then release the parking brake AFTER you are underway in 1st gear? Not simultaneously.
Seems like you are over thinking this.