I grease mine from the bottom. On the passenger side I have lots of room. I have a grease gun with a 24" hose that will flex and reach the fitting. I just give it a couple of stokes of grease and so far I have not had any problems. You do not want to over grease that bearing or else you will really have a mess with the grease getting on the fan belts.
You can also get it from inside the coach, but I hate taking the cover off the top of the engine box. Lots of work on that, but once you lift the bed up you can get on top of the exhaust manifold and grease it from there. Not easy though.