As modern-day neuroscience tells us, we are never in touch with the present, because neural information-processing itself takes time. Signals take time to travel from your sensory organs along the multiple neuronal pathways in your body to your brain, and they take time to be processed and transformed into objects, scenes, and complex situations. So, strictly speaking, what you are experiencing as the present moment is actually the past.

You cannot be a rational subject without veto-control on the level of mental action.

Speaking as a phenomenologist, it seems to me that a considerable portion of mind wandering actually is "mental avoidance behaviour", an attempt to cope with adverse internal stimuli or to protect oneself from a deeper processing of information that threatens self-esteem.

If we lose the ability in question for a single moment only, we are immediately being hijacked by an aggressive little "Think me!" and our mind begins to wander.

I believe that gut feelings, the sense of balance, and spatial self-perception are so firmly coupled to our biological body that we will never be able to leave it experientially on a permanent basis.

I believe that if we would carefully apply the distinction between transparency and opacity to the different layers of the human self-model, looking at self-consciousness in a much more careful and fine-grained manner, then we might also arrive at a new answer to your original question: What a "first-person perspective" really is.

The notion of a conscious model of oneself as an individual entity actively trying to establish epistemic relations to the world and to oneself, I think, comes very close to what we traditionally mean by notions like "subjectivity".