"after just one trip to the field and a few weeks living in the ever hotter south Texas garage "

Not necessarily due to your covering expertise, or lack of. I once built my own camper shell because there were none comercially made that satisfied my requirements. We live in San Diego, where the humidity is high. On our virst summer vacation trip to Arizona, the wood I used, dried out, shrank, and put wrinkles (across the grain) in the trailer type aluminum siding I had used. A few days back in San Diego, and things were back to normal.

Les