I was faced with a similar thought/feeling/fear regarding the lack of thickness on my RV roof when drilling/screwing down solar panels. It seemed really thin.
Here's a link to what I did and how my install went:
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30217540.cfm
Summary: Instead of 4 brackets per panel, I ended up with 8. I also used 3M double sided tape in between the bracket and the roof to give them extra grip/holding power. They seem 100% unmovable still one year later.
If you are like me, you probably had a little fun coming up with your solution. I applaud your ingenuity. The adjustable furniture feet to give your panels extra support across the span are crucial. You might consider using 3M double sided tape to hold them down to your roof so the panels don't bounce while driving down the road.
Enjoy your sunshine power!
Chris
PS: Isn't solar addictive??