i have a 36volt trolling motor on the front of my 20' procraft, i also have a 12volt that was given to me. i have been thinking about mounting the 12 volt on the back of the boat. my thinking is that if my motor ever quits i can use the rear trolling motor to get my boat on the trailer. has anyone else done this or am i just being absurd.

I carry an extra TM when I go fishing but I leave it in my truck in case my bow mount decides to quit - I have an extra I can put on and get back to fishing and not ruin the trip.  

Haven't thought about your idea - if I was concerned it may be easier to keep an extra battery in the boat to start you big motor with?  

Wouldn't it be easier to use the trailor winch?..................Al

I fish some lakes that I can only utilize my bow mount TM on my 18.5 glass boat due to HP restrictions.  That, of course, includes unlaoding and loading from the trailer.

With some practice you can use the TM to get a run at the trailer so that you only have to winch it about the last quarter of the way on.  The trick is to get the trailer in the water to the correct depth depending on your trailer and the depth of the particular ramp.  The most difficult part of course is getting the boat lined up and keeping it straight.  It helps if you keep the skeg of the big motor in the water part way to act as a keel so the boat won't want to turn as much.

So in my opinion I'd don't think I'd carry along the extra TM just for that purpose.

If your just worried about if your main motor does out, your bow mount should do the job, you don't need to add the 12V onto the back.  My reverse went out on my main motor so I use the bow 12V on my boat when I'm getting it on and off the trailer or pulling next to someone.  I just get as far on the trailer as I can, and then start the main motor to push the rest of the way.  If all else the trailer wrench can pull the boat up.

I think adding the extra 12V maybe going over board.  Plus that's another thing to wire and something else to get in your way when you trying to land a big one.