Sounds cheesey, but you could make some stones out of the foam board from lowes or home depot and paint them gray or what ever color. then use stickey velcrow strips to adhere them to the blind that way you can take them off when you are hunting some where different. and like some one else said put your blind next to a pile of rocks and you would look like another pile of rocks. I have similar problems where i hunt particularly in late seasn when all of the launches freeze in and i'm stuck hunting shorelines and the cover sucks. It's tough to hide sometimes and you just have to be creative and make the best of it. Another thing to consider is if you are down in your blind and very still, are the birds flairing because of you for sure, or is it some thing else like shine on your decoys or any number of things.