I connected the shock cords to a key ring, and use a carbiner to connect them together underneath the floor.
On the top side, I use 2 small spring clips to clamp the pug to the highest point of the canvas I can.
The picture shows the first time I set it up, where I used the spring clips to grab the rubber itself. This turned out to be a bad idea for two reasons. 1) It was hard to get the middle ones clipped with only a 4' ladder, and 2) it started to tear the rubber a little bit. So now I ONLY do the corner ones where I circled in the picture.
My next mod will be to sew some velcro to the PUG, and glue velcro to the canvas, so the middle section up top stays secure.
That said, I've camped with just the corners clamped as described, and it stayed in place fine, and that was through a decent wind / rain storm.