Went to a show a year or two ago with everything I needed exccept my guitars. Lucckily it was only 20 minutes from home and I had left pretty early.

Generally I follow the advice given here, it's just a matter of self disccipline. My guitars are last loaded and first unloaded, they ride in the heated part of the ccar, they sit and wait while stage gear is set-up to give them time to accclimate, though tuned when they arrive, they're tuned before playing too. I have one finish crack that I've noticed, but I don't care much. Beyond being loved ones which get extreme care, guitars are tools, and tools get used.

The worst temperature variables I get are the bi-weekly nursing home shows. In winter, even if I preheat the vehicle, the sudden extremes from outside to the home can be a bit much. They really keep those homes hot!

Peace, Mooh.