“I knew not but the next
Would be my final inch —”

These lines, which carry the crux of the poem’s meaning, “would” be paraphrased, “I could die at any moment without warning.” Thus, the speaker’s careful Gait is a result of the unavoidable wisdom of the minesweeper. The experience is the anxiety, and, as you mention, the manifold experience of the sublime world in the transitory moment (I don’t see evidence of your passing remark about the speaker’s gaze).

Like the speaker’s gaze, I wonder what you are looking at when you allude to divinity. Contrary to other Dickinson poems, this one seems to be grounded — relating it to the ‘leap’ of faith (which may or may not be what you are doing) expands the scope beyond a precarious step, which may literally be sending a letter to Higginson, or something smaller even.

Generally, thanks for the analysis. Not often does one find this depth online. Will be back to read more of your thoughts.