Trazodone is notorious for its anticholinergic properties (which dry up your mouth and mucous membranes). I've heard of people literally having to keep a water bottle by the bed so they can drink it the instant they wake up.

HCTZ is drying too since it pulls water out of your cells and makes you urinate more often. In fact, much of the medication you're taking causes dry mouth. I've heard there is a prescription drug that helps this, but can't remember what it is. Biotene can also be helpful, though it doesn't work for everybody; I just drink a ton of water and hope for the best.