[@Dog] I'm using 5e rules as written with very few exceptions -- homebrew rules that usually add to the game rather than detract or change. That applies to AC. Meet to beat, as it goes. Otherwise the defender successfully blocked or dodged your attack. There are already damage resistances and invulnerabilities, as well as damage threshold (where you must do minimum x damage to deal damage at all), though those are usually for objects or structures.

For uneventful regular travel, we'll just account for supplies such as rations or scavenging. Where travel is intended to be the focus of storytelling and mechanics, we'll start to tracks things a little more meticulously. In a world of high magic, I tend to say that resources aren't terribly difficult to acquire as long as you don't just ignore it all or make [i]really bad[/i] decisions.