I also agree with the double Rainbow suggestion. Even the double is just a little tight for the two of us (diet time).
We sealed every place a thread passes through fabric, twice on the inside and three times on the outside and have had no leaks, even during a 24 hour storm on the AT last year. The bathtub floor works well, if you pitch it correctly. We learned the hard way after getting some rain splash. You peg the floor almost straight out following the long side, at almost a right angle to the short side, and this lifts the floor up to help for the bathtub.