You can replace the bulb through the access panel, it's a hard reach but it can be done. Just make sure the old gasket comes out with the bulb and if it's doesn't you will need to remove it by hand. It's probably quicker to remove the entire headlight assembly as it's such a hard reach, you might find it easier than I did.
I spent an hour fighting with the access panel unable to get the new bulb locked in place. Other than a huge bruise on my wrist, I had nothing to show for my efforts. I then googled and saw your comment on the old gasket. 2 minutes later I am good to go other than feeling a little sheepish. You have my nomination for the Nobel prize.