On my 87 E34, that grease fitting is on the rudder tube near the top facing the transom so access is difficult. I was able to squeeze my self in there a few years ago and did empty almost a full tube of grease but the grease gun fitting kept falling off the zerk fitting so about half of the grease wound up on the outside of the rudder tube rather than inside, a mess to clean up. It is really a two man job, one to hold the grease gun fitting tightly against the zerk fitting and the other to pump the grease gun. The second person is also needed to pull you out of there.
They do make grease guns with a "pistol" handle for one hand pumping but I doubt if there is sufficient pressure to pump the grease into the rudder tube, they also make an electrically powered grease gun but $$. I had the yard do the grease job on my last haulout, Two men, 1/2 hr and a tube of grease, about $150.
I don't know why EY put the zerk fitting facing the transom, if put facing starbord, the job would have been much easier.