I change my oil/filter at the same time as my valve clearance check. The valve covers are off for the clearance check so I pour the oil into the top of the engine. It is easy, quick and the oil all drains to the sump. By the way, I carry a wrench to remove the plastic adapter if I need to add oil while on the road but have never needed to use it. My engine does not use oil between changes.
A hint on the amount from Jim B at Rose Farms -- Fill the filter completely to the top before you re-install it. Then add three liters of oil to the sump. That will be the correct amount.