DH is VERY squishy. We honestly are the true glass cannon as I don't these issues with Wizards. I'm soloing Inferno and I'm up to act 2 right now and the key to surviving so much is to just straight up use Smoke Screen as much as possible with the Lingering Fog rune. Along with preparation, you can tank mobs for a long time by immuning and you can skip stuff/get away very easily.
This is the build I'm using as I solo inferno. I'm using a 2h xbow and I'm stacking increased crit chance/damage wherever possible. Along with Sharpshooter, this is an EXTREMELY powerful build. I'm one shotting things and doing crazy amounts of damage.