Having some experience with towing an electric vehicle (the Electro-Metro) with a gasoline vehicle (Chevy S10), I can tell you that it is completely possible to push the gasser around from behind with the electric.
Several times this winter, I was towing the day after a snowstorm, and my (two-wheel drive) truck is pretty poor on snow.
One time, my truck tire got off the really smooth plowed part of the road just enough to start slipping, and I got stuck.
No problem, I put the truck in neutral, hopped in the attached Electro-Metro, flipped it on, and easily used the Metro to push the S10 right back into the clear part of the road. It was great!
I am not sure exactly how steering of a gas car would be effected while being pushed from behind from an electric though in general driving.
Another great "pusher-trailer" to take a look at is
Mr Sharkey's. It's pretty slick and features a couple different ways to be used.