I have seen on Denny Gulvas' video where they took their birds with the bow without a blind. What they did was to stand up, behind a tree, Just to the left of the tree, so the tree would hide their right arm moving when they drew back. It worked on the video.

Personally, I've never been able to sit still long enough when hunting from my knees so that I could draw from my knees. Sitting on your rump and drawng would be darn near impossible. So, I'd think standing behind a tree would be a good way to try it. Another way I've done it in the past was to make a natural blind (blowdowns, honeysuckle patches, ect), then sit on a chair behind the natural blind. This was more comfortable, and the blind broke me up pretty well.

Hope this helps,

Slice