Another thing to consider, do you have some spots that will be fairly "permanent." Traditional sweet spots along field edges and so on? If so, and you can leave it there year round, you might consider building one. I know guys who have (and I am considering doing so) built blinds out of heavy duty wire fencing panels that you can bend into a circle. The fencing becomes the frame, shapped like a hay bale on the edge of a field. They cover the whole thing with black plastic (so it stays nice and dark/no shadows), then burlap and camo paint the whole deal or cover it with hay, grass or whatever matches the surrounding. Usually much less than a quality hub style blind in price (maybe $50-$75 in materials max), much more solid and blends in better. You can get 3-4 people in them sometimes so beginning bowhunters can tag along. Again, not very portable but nice if you have the spot picked out and can leave it there.

P.S. A good idea for the windows in those situations is to affix replacement screens you can buy for a hub style blind. Or strips of camo ghilie material via a curain mechanism you can push aside when the time is right. No black porthole effect.