I hunt them without a popup blind. It's definitely doable, but you need to hide yourself well, from all angles. A ghillie suit can work great, if you can take the heat and can shoot without hanging up on something.
I prefer to nestle in to some natural cover and pile some downed limbs to fill in gaps. I also take a piece of burlap with me for the same purpose. Just make sure you are hidden from behind.
Here are a couple of pics from inside a couple of different set ups from last year.
The first pic was from my setup on opening morning. I was absolutely covered up with birds. My mistake was not being hidden well enough from behind. A big sneaky gobbler busted me from 5 feet away when I went to draw on a bird that was molesting my decoy. About gave me a heart attack.
The second picture was a better setup. I had an old blow down behind me. One thing I believe is critical to success is to have some good decoys. My AvianX dekes worked perfectly, especially the 1/4 strut jake. I've never seen gobblers get so worked up over a decoy.