I'd feel pretty comfy in the back seat with a 500 foot ceiling, if the guy in the front seat was someone I trusted.
The part of that I don't like is 'bumping' the bottom of that ceiling when it's right around 499 feet and the wings keep catching frost and flakes of ice
Even a twin flying twice that high, in those conditions, over water really gives me the willies.
Lots of ways to get yourself killed via gravity; denial feels like a comfortable safety net………until it ain't. (What you don't know might not hurt, but it can sure get you killed real fast.)
