You’re right, we can’t see the toolbar or camera window when switching to other modes. As such you need to setup your joystick to control the drone mode and to toggle in/out of it. If you need more buttons then plug in a second joystick or something.
Here’s a tip. There’s several camera modes… cockpit view, drone mode, external view, and slew mode. Let’s say you want to program 1 button for the “up” action. That one button can be assigned to “up” for each of those modes. You won’t have any conflicts having 1 button assigned to multiple commands in this case.