I have a Rainbow Tarptent - that is close quarters for two people at 40# across!
I have backpacked for 10 days on the A.T. with a 5'8 son in it (and I was overweight at the time!). I have backpacked for 4 day weekends with my husband with it, and I have backpacked 10 days with a friend on the A.T.
Yes, it was close quarters; however, we are not "tent people" - meaning, we prefer to use our tents only for sleeping purposes. We do generally abide by "hiker midnight" and hit the sack by 9pm. And, yes, there are nights where it is raining, so we go to be early. However, for the most part, my waking camp experience is out of the tent. For this reason, it has never been "too close."