Rsn48,
I have used a tortoise machine or a snap coil machine on a turnout that is at the end of a auto reversing loop. The key is the electronics. I used PSX-AR from Tony's train exchange. (I use dcc).
The PSX-AR will mange the auto reverse as well as throw the turnout on the reverse loop.
As I used a snap coil machine, I was able to place gaps at the frog end of the turnout. The PSX-AR detects so fast, that it changes the polarity and throws the turnout before the lead loco gets from the joiner on the turnout to the frog!
Brendan.