Sorry for the tardy reply. Mike and Kelly are away right now doing the Christmas thing. I'd be a little cautious in assuming you can get steel 100s. The VAST majority of their tanks are alu 80s. They have some steels there, but I think there's only a handful. I'd recommend taking your own if you can. Mid-day fills are normally pretty simple to manage. Their shop is only a few hundred feet from the dock and they normally meet boats with wagons to tote stuff.
Four dives up here is an ambitious day. Assuming you're on a charter with DD, you might want to to see if you're coming in at noon, or spending the time on the lake. If there's a full group, and each of you takes four tanks, the skipper might have something to say about it. That's a lot of gear to carry and stow...