I have a motor mount on my TI that fits into the rod holders, it will fit pretty much any transom mount gas or trolling motor out there. I have a 2 hp gas on mine, but it could just as easily be electric. I have had the same motor on my old Oasis, and also my Revolution. However on the revo (or outback) you may need to counter weight the motor. Here is a link to a mount you can buy if you don't want to make one yourself.http://islandhopperoutboards.com/hobiekayakmounts.html
When running the motor on my Revolution I felt very insecure in the ocean without my weighted keel (a 25 lb torpedo shaped weight mounted under the boat (about a foot down by spectra string) to prevent the kayak from being able to be tipped over in rough conditions or sailing (specifically in the ocean). I just use a 2 ft piece of 2 inch PVC tubing filled with lead shot (can be bought at any scuba shop). Hobie also makes pontoon outriggers called sidekicks that would serve the same purpose. If your just goin out on lakes and are natrually stable ( I'm not) you might be fine with nothing on an outback (a little more stable than my Revo). Even if you do tip over, as long as you get the motor cleaned and dry quickly, it'll likely survive ok. Good luck getting the battery from the bottom of the lake though (LOL).
Here is another related forum topic describing the same stuffviewtopic.php?f=69&t=40482
Hope this helps