I installed a push-button in my QX7 for DLG launch mode. I can reach it while maintaining a firm grip with my other three fingers on the radio, and it has a rounded shape which is easy to park my index finger on or next-to without accidentally pressing it. It has a nice firm positive action when pressed.
Where I installed it there is enough space inside for the threaded body and terminals. Source is Digikey, part number is EG4575-ND

This is an idea I posted earlier here.
No-cost fixture to check c.g. - raid the kids' Lego box!
This one yields 54mm from leading edge, for my Hawk.
You can use cylinders or heads, and easily fine tune the fixture with tape or foam tape.
There is some foam tape on top of the rails to prevent slippage.