We have all been discussing the possibility of using drawer slides for a pop-up. I realized there is a problem though. My brother-in-law pointed out that the weight rating on these is at 90 degree angle from the slide. In other words these are meant to mount horizontally and the weight they support is from pushing down on the ends.
If you mount them vertically they will support the weight up and down still, but will easily flex side to side (along the flat part).
One way around this would be to mount the slide in a notch routed out of both the trailer and the pop-up wall.
If you look at a regular drawer you will see there is a space between the side of the drawer and the place it goes in. Using this notch will practically eliminate the space and also provide a great amount of structural strength.