I lost a rear cylinder head gasket at about 15500 mi.Now at 17000 mi and rear cylinder base O-ring is leakin.
When you say you 'lost' it, did they replace it with the 16801-07A? If so, that explains why you're seeing the oil out the bottom. The 'A' gasket does a pretty good job of stopping the leak that leaked oil over the top of the fins, where most of us saw it first. The problem is that when the 'A' gasket fails, as it usually does, it fails in a slightly different way that allows the oil returning from the head to migrate sideways to the stud pockets and run down the studs and fill the the pockets around them up with oil. Once oil makes it to the bottom of the pockets, there is no gasket in that area to keep it from seeping out between the cylinder and case. This is why you're now seeing it come out the bottom.
When you see this leak it is natural to first think that the base o-ring is leaking, but that isn't necessarily so. The base o-ring goes around the cylinder spigot but that is located inside the bolt circle of the studs. The base o-ring's job is to keep oil from coming up from the case, not down the studs. Since the studs are supposed to be dry, there isn't any sense in putting a gasket outside their bolt circle to hold in oil that isn't supposed to be there. All of this doesn't really matter because when they replace the head gasket this time they will replace all of the o-rings too.
I'm living with the exact same failure, and have been for about 5,000 miles. I have just been cleaning off the oil film and riding it until they come up with a REAL fix.
In short, you've still got a leaking head gasket.