When you google for images of (canoe & bike) you find two basic solutions to towing a canoe with a bike.  

1. A traditional axle mounted tralier is modified to have a tongue long enough to load/support the canoe/kayak on the trailer.

2. A seat post or carrier mounted pole connects to the front of the boat, the boat servers as the "trailer frame" with a canoe dolly (wheels that attach to the boat for moving by hand) for wheels.

Solution 2 offers the advantage of less material and more a portable trailering solution.  With this solution the bike and trailer easily fit in most canoes, so you have a [fully amphibious combination](http://outdoors.stackexchange.com/questions/6948/how-to-carry-a-bicycle-in-a-canoe). 

Is there any significant safety considerations when towing with a bike from a higher or a lower tow connection on the bike?