I asked HK if they had an application for this and they said:
Hi DICK ,
Thanks for contacting the HobbyKing Support Team.
Unfortunately we don't carry such switches because they really weight a lot, and are not reliable enough. That is why all batteries get unplugged instead of switched off.
However there are quite a few ESC's with switches built in the electronic circuit, so you actually can switch the ESC off with real soft switch.
Sorry that I couldn't provide you a ready solution.
Have a great day!
Thanks for emailing support.
If you have any other questions, please let me know.
Regards.
Jarrad
HobbyKing Support Team