The no zoom is the first problem, second is once you shoot there's too much movement if your camera is attached to the bow. Inherently filming yourself will be tough to any decent footage. Solved system is one of the better ones around. I haven't bought it yet, but it lets you use any camera so you have a zoom when needed and secondly the head is way more stable through the shot. They have a bunch of sample films on their page you can see.
solvidsystems.com