Does a pleasant voice speak to you through your comm system and say "Sensors indicate blood moon will initiate in t-minus 4 hrs"? Because THAT would totally fit the HUD you are describing right now....
What they really should do is remove the time entirely and let you scratch or paint hash marks into the wall of your base to keep track of the days, that would be more fitting of the current survival game.
Now if we were being depicted as wearing power suits with projected heads up displays on the visor of our armored helmet then I'd be all for clocks and compasses floating in the air in front of me. We could have all player status data displayed on the screen and color overlays to show heatmap status and structural integrity and ore deposits underground, and radar blips on an overhead minimap to know where all the zombies are around us.
Don't forget windspeed, temperature, altitude, target lock-on and lead assistance reticles...