I'm looking too. I would like a thin, strong panel. These things must be durable. People seldom complain.
An area that makes more power difference for people who don't sit still is the alternator. Specifically the regulator for the alternator. Automotive regulators are designed to charge starting batteries. These regulators can be replaced, but it gets complicated. The simple manual way to properly charge a house battery from an auto regulator is to let it charge up to about 90% of capacity, and let the solar slowly do the remaining 10%. The solar, and plug in chargers (if one exists) should be three stage and specifically mention the battery type. "Smart" chargers aren't as good.
Xantrec is the easy higher end choice for all these chargers, although others like Outback are in the same class. In my build I'm installing Three Xantrec products: XAR on one of two alternators, C40 for solar, and RV3000 for inverter and plug-in charger.
Don't mean to redirect the thread. Buying the right solar panels is my primary to-do electrical item.
Oh, as far as panels, if the solar charger can handle higher voltage input (better ones can handle up to 48v), higher voltages can be sent from the roof and lowered to 12v by the charger. This allow smaller wire and more efficient transfer - more bang for the buck. But only if the solar charger can do multiple voltages.. For a single panel install I wouldn't worry about it.