I have a Eureka Backcountry 1. It will hold a little more than 1 man (ie you could put 2 in there and sleep in an emergency or 3 sitting. It has a bathtub bottom. In a HUGE deluge up in the Catskills (3 inches in 90 minutes), it was 100% waterproof. To me, the only reasons to have a tent are:1. To stay dry2. To stay warmer (in winter camping)Aside from that, I'd just sleep on the ground.
This is an Australian product, but I've always wanted one of these, for the same reasons you're looking for one http://www.blackwolf.com.au/product-details.php?product_id=135&category_id=22