Rusty
Most of us have this problem, I used to do a lot of rock climbing, high altitude climbing when much younger so you think I wouldn't suffer from vertigo. BUT
even today after 8000 hours, with doors off at high altitude get that vertigo feeling despite doing a lot of long lining with no door on. Don't get the effect when long lining, only get it when dropping parachutists from 8000 ft and only when they have left the aircraft ! The only other time time was with Richard Hammond from top gear when we were trying to dip a bucket into a cloud at 5000 ft, oh boy really had a problem with that along with Hammond screaming he couldn't handle not having a door on.
You do get used to it !!!