3 feet deep "single-sided walk-in closet or a narrow walk-in closet/passage - In professional contexts, it would be referred to by its function and layout, such as "narrow, single-sided walk-in closet," or simply "walk-in closet," as it meets the minimum requirement of being a space one can physically enter."
Technically, you will have less room for crap but for sure more accessible and your bomber jackets will be happier..