Reading the manual multiple times is a good idea. I actually got an electronic copy of it from CLC that I started reading immediately. The lead time on my kit was about 4 weeks, so that was plenty of time to get ahead of the game. I simply emailed them mentioning my order, etc and they sent it to me.
As for the fabric for the bottom. I ran short from the perspective that I did not have two lengths long enough to cover the bottom and the transom as singular pieces. So I simply did the ‘ layer approach with thumb tacks like you might have seen with the top to the sides. Here is a picture of it. It turned out great without any complications. The reason I ran short on the length was simply due to a mis-cut for one of the sides. Just take your time and I’m sure you’ll get it right on the first try. If not, then at least you know there is an easy and simple fix. 🙂
Good luck!