I think that you should probably overline. You need to be able to load your rod as rapidly as possible and often without too much line out. It sounds like you like the feel of overllining to begin with and often the heavier line will be an advantgage in windier situations. Without quite a bit of experience it is difficult to see bones farther than 70 ft, so real long casts aren't usually necessary.
I usually have 9 to 12 ft of leader and try to drop the fly well in front of the fish, so the 'splash' from the flyline shouldn't be an issue. The are sensitive to the shadow, however. Some guides recommend dropping the fly right on top of the fish and I have had this work; the fish bolts but comes right back and grabs the fly.
I haven't fished cold salt water lines but I have tried bone fishing with a cold water bass taper line and it didn't work very well. The air and water temp turned it into a noodle. I have used SA bonefish taper or tarpon taper in a 9 wt, but the RIO bonefish taper in a sand color may be better. Wonderline is quite good as well.