Stand By For Explosive Decompression

Just as the visor helmet includes a bubble helmet...

The standard vacc-suit includes a skinsuit.

A skinsuit and bubble helmet are the base that all the other suits are built up from.  It's all modular!

But, let's say you're sitting there in your acceleration couch, in your skinsuit, helmet off and your ears pop and the cabin suddenly gets foggy.

Now what?

You reach behind you and grab the bubble helmet that's mounted on the head rest, put it on.

Then you connect the umbilical line from the seat's mini-tank to the fitting on your skinsuit.  That mini-tank is hooked to the ship's central umbilical feed so you're not limited by tank capacity until you actually leave your station.

Because the skinsuit and bubble are the core of the other suits, you don't have to remove them to get a suit with more DR and PF!  Everybody wins!

At higher TL the bubble helmet is replaced by a flexible space helmet in the headrest to save space.  It's the same form factor as the bubble, you just give up some DR while wearing it alone.

A change I make from the rules as written is the helmet neck-ring.

A real-life pressure suit has a ring with seals on it and the helmet clamps down to it.  Then the helmet doesn't rotate with the wearer's head.

TL9+ suits are counter-pressure rather than atmospheric pressurized.  So the "neck ring" is simply a higher collar and the helmet has a flexible skirt which mates with it.  This allows the helmet to be smaller and lets it move with the wearer's head.