Pa,
I hunt exclusively on the ground also. When bowhunting, If i couldn't put my blind out around a week or more earlier, i usually go natural. When doing this i usually try and use a downed tree or heavy brush. I may add some more cover but not too much in an attempt not to change his environment all that much.

When gun hunting i'll use the pop up that day provided my setup will allow me to see them coming in at a distance greater that 40 or more yards. When using the pop up i'll try set it up where it can not be easily outlined by the deer

If the weather is rain or heavy snow i'll use the pop up no matter what. This way i get to stay out there all day when everyone else stayed home