John: You're absolutely right that the weak point is the attachment/charging arrangement on the panel.
I wish I knew exactly what I did wrong. I was in a desert area (New Mexico), so maybe sand got in there. It's not clear. But it didn't last for more than one hour. Maybe it was broken before I even got into the desert (I had little time to the test it before I left - it seemed to work, but who knows).
On the other hand, Brunton Rolls make it up Everest and other inhospitable environments, so I would give it another go. However, I would buy it from a place that has a good return policy, like REI.
The other panel I used (I don't remember the brand), also broke before I got started, or at least, it wasn't charging the way I thought. It could be user error.
Given all your electronics, you are a perfect candidate for a solar roll. Give it a shot and tell me how it goes!