I've smoked seven different sessions of ribs (about 20 racks total) and found very quickly that:
1. Yellow mustard schmear, dry rubbed, and plastic wrapped in fridge overnight is a solid system ... moist and tender every time.
2. Direct liquid (spritzing with apple juice) produces slightly better outcomes than a water pan.
3. Marinating the ribs produces a very different flavor profile and texture (due to the salt in the marinade).
The foiling method is outstanding for traditional smokers ... but I've found it to be unnecessary with the #3.
With regard to environmental factors, I do live in a humid area (Texas Gulf Coast) but I doubt that this plays a role; altitude, however, is a concern for some folks.
My two cents ... an overnight prep and held 12-24 hours in the fridge, followed by heavy spritzes of apple juice at the second and fourth hour mark is the easiest method for tender, juicy ribs.