Immersive no-HUD, first-person gameplay

Game visuals look of course more immersive with the HUD off (tab-tab) and seen from first person perspective. But without the HUD, even if I look at cockpit displays, I miss perceptions that a human being would not miss.

For example, as a HUD-free player in 1st person...

• I cannot tell if my helmet is open?
  
• I cannot tell if health/O2/H2 are low (only generic "pain sound" when it's too late)?
  
• I cannot feel where up or down is?
  
• I cannot feel if I am overburdened?
  
• I cannot read button labels?

All the things in the HUD are not in the same category. E.g. hundreds of GPS waypoints and antennas, you can argue, are OP and break immersion, so it's good to be able to switch them off. My "human perception" however, I do not want to switch off.

What about a "fourth" tab option that hides only GPS markers, antenna markers, and the toolbar? Optimally, it would then only show a minimalist summary of gravity, backpack, life support/helmet/jetpack, temp/atmosphere displays in one corner, from which I can tell "if I'm about to die or not".

I agree that having more than three tab-able HUD variants slows down quick-switching, so it should not literally be the fourth. Maybe let players choose which variant they want to be tab-able. E.g. advanced players could choose to replace the default help-text-enhanced HUD with this minimalist HUD variant in the tab order.

PS: When I use alt-tab to switch to another Windows app, that also hides the HUD in Space Engineers, somehow it cannot tell the difference.