Maybe the dragon shouldn't have landed in front of me, but with a solid survival check, I had found a depression in a cliff face, which is where I made my camp (a pseudo-cave, of sorts), so it was land or don't engage. The playtest wouldn't offer too much information if we went with "don't engage."
The Desert's Thirst would have been a cool idea, but I was loaded with comparable cure spells, anyway.
It seems the biggest problem is that the dragon landed... Should we have maybe run the same encounter with a frost giant? It's the same CR. Or even keep the blue dragon, no pseudo-cave. I could just use a tree canopy for stealth and hide until it lands or leaves - its perception isn't that great. Flying as fast as it does and trying to do the drive by tactic, I'm sure I'd break line of sight in relatively short order.