You're always playing chords well away from the nut, and moving up and down the neck a lot. You just don't need a capo, and it would only get in the way. You need to learn the full chord shapes and use them everywhere - you very rarely need to use open strings. You don't actually have to learn what the chords are called, just their relationship with each other within the same key, so if the key changes upwards a tone, you move the lot two frets up and play an identical set of shapes. Think 1, 4, 6 rather than G,C and D. Remember where the key chord is on the neck and use that as a base.