A man standing six-feet tall on Earth, 'retains' hydrostatic pressure of about three psi at his feet - the 'feel' is balanced by vascular pump-action through-out the body from head to toe, and by capillary action, and by muscle-to-bone attachment tension ... it's this total 'retention' pressure which is of interest hereïn.
The zip-suit is comprised of, a mostly evacuated 7% atmosphere (1psi) outer-suit, and a 20% atmosphere (3psi) oxygen-pressurized inner-suit 'under-wear' with invert-collars around the upper thigh and upper arms, and attached to the helmet about the neck, consisting of a pressure retention cloth of solid lubricanted elliptic weave whose fibers detentelessly glide around themselves for maximal volume retension, and least pressure stiffness. Additional 'chemical' suit (skin-ointments) may be added to maintain wet-surface vapor-pressure within the outer-suit. The outer-suit remains flexible at 1psi, while the inner-suit offers little restriction on movement at 3psi - either can maintain the full 3psi plus margin should one fail. In the case both inner and outer suits fail, the lungs expand to fill the outermost (extra) hex-weave retention mesh, and the air pressure regulator switches to pulsated mode to breath for the wearer, feeling like bobbing in 2 meters of water. [On the ordinary threshold of needing to equalize the inner ear pressure]
Such a suit is easy to don and wear, without stiffness. The 'feel' of such a suit in space-vacuum is that of standing on Earth ... a comfortable posture for hours.