I've been 2R'ing overnighters in my Puma for 3 years now, no frame, no floor, no problems. I don't see many others with a similar setup so it makes me a little nervous, but I've had nothing but great times.
My first trip wasn't well planned as I had no idea what I was doing, but last year I ran the Chama twice and the San Juan 3 times from Sand Island to Mexican Hat, and the Gila Wilderness run. My setup worked fine, although no flips or pins to know how well it would really hold up (I think I rigged to flip...). The little Ecosys toilet is small and fits on the bottom of the floor, no issues, but I bought the expensive little Ecosys because I knew I had little space to work with.
I run a strap across the bottom and use dry bags and clip everything to it or to thwart handles.
Some photos and descriptions in this thread