Wow, that sounds complicated. You could just use a 555 timer one shot to power the 555 flasher so that it only flashes for ten seconds (or twelve or whatever you want) so it doesn't matter if you leave the TS switch on since it stops flashing after the timed interval if you do. Next time you go to use it, you notice it's in the on (left or right) position and center it then use it as normal. Or the really simple solution I use: a 12V buzzer that beeps as the TS flashes to remind you to turn it off.