All of our pop ups we had in the past, at some point in time, had screws come loose. What I always did, was move to the next larger size that would get a bite in the wood, and, before installing the new screws, I would soak the screw hole with some two part epoxy. Then install the screw before the epoxy sets. I never had a replaced screw back out after using the epoxy. On a load bearing screw, such as you are describing, I would think the nut and bolt with a fender washer, to spread the load out some, would be a better choice. Just make sure the bolt isn't so long, that it interferes with opening or closing the camper.