This is my 14 year experience in mountain rescue: if you have a good reference near the cockpit point of view you don't need more than that. In case you are way above any reference around you, best thing is to have a good situational awareness changing references and not staring at the same stone, branch, tree, ....all the time. Trust your hoist man in case you are not sure if you are doing a good hover, but you have to find out what best fits you to do the job ...enjoy it while you can !!!