Aggie: I do all my distance rides all alone and completely sef-supported ie: I carry all my food and all my water. and I have loved every single one of those rides. NM does pretty much all their organized events on Sun and I can't attend due to other obligations. Since this is an organized event you won't really be alone. You might log some miles between people but you'll either catch up with a group at a food stop, or have a group catch up with you that you'll ride with for awhile, or you may just find someone early on that rides your pace and do the whole route together.

My vote: do the century! You'll love it (not to mention something you can brag about to the DH )