Yes, riding in the turret gunner's spot would give you a nice pucker factor! We had a number of marines killed by snipers in Fallujah in this fashion. The worst was setting up in a hasty vehicle checkpoint and you had to watch everywhere while trying to make yourself as small a target as possible. I was usually in an MTVR for this so we were up even higher.Standing up that high to fire the 0.50 cal would give you a good view over the landscape. But LOS is reciprocal...
I had one of my marine's patrol get caught like this and after the smoked cleared they crossed over to the peninsula. While they were exiting their vehicles one of the turret gunner's asked his buddy to see what was stuck in his right shoulder. They found that he a 7.62 round stuck half in his flak vest and half in his right shoulder.