When doing my wildlife photography and I have a fair bit to carry, I just use a camo kit bag. It is long enough for tripod and Wimberley, carries my camo netting, stool, etc. etc.
It's easy to carry as a backpack, handles work as back straps. Also, because its so long, it actually helps with my back. Its comfortable. If I remember correctly, it only cost me about £20.
Works well for me.