Thanks for getting back...
1) --keep-complete in splitter - yes. I figured with the long
routes and few nodes that this could be a possible point of
failure so I made sure to add it.
2) iWowik sent a PM suggesting that some of the important tags
were incorrect and/or missing and he was addressing some of them.
One suggestion of his was to use Key:ferry to help maintain
connectivity to the roads. Wiki states "With route=ferry, this tag
can take the highway=* classification
of the roads it connects, like a bridge." So the service /
trunk_link issue Andrzej noted is very interesting. If not given,
what road classification does the routing engine see for the
ferry?
3) I made sure to untick the Toll Road avoidance thinking this may be an issue as well, but no change.
OK... so it looks like there may be several issues at work here. I didn't realize that ferries were such a can of worms both from a mapping and a routing perspective. I expect that this service road issue is a common problem with ferry mapping. Also, given the impact that ferries can have on travel distance and time, unless explicitly avoided, perhaps ferries should always be given a pretty high priority in routing? They're more than just a stretch of 30km/hr highway.
Thanks for looking into this!