You are a scientist named John Vendetta. You were kidnapped with other Black Mesa personel after The Black Mesa Incident. The kidnappers tried to get from you critical information about the Resonance Cascade and then kill you. Thanks to the HEV suit, it seems like you are the only one who survived and you need to find out who's behind all of this. It's time for REVENGE.
I was once toying around with custom skyboxes myself. Better don't they ruined more Black Mesa maps for me then they benefited as many hills in the background were mostly out of place.
As for the screen. Some bushes near the water and perhaps even water plants might do nicely here.
Thanks for this idea! I wanted to add this but completly forgot.