Thank you!
The molds for the wrecks were made with Oyumaru (a reusable thermoplastic molding material). Any greenstuff casts that weren't neat enough to use for the sinking ships were simply cut to bits to serve in the debris markers.
I also discovered I had a small historical ship that included rowboats in my stash, so I made some casts of those as well. Now several of the wreck and debris markers have a single rowboat escaping the demise of the mother vessel.

And the first batch is done:

With cute little banners: (that were an absolute bear to paint... The banners are roughly 6-7 mm tall!)

Each of the Monitor banners features the symbol for Barak Varr, followed by an icon copied from the original paper banners that came with the Monitors.
Pictures aren't optimal, as I was painting outside and when time came to take pictures I had to choose from deep shadows or glaring bright sun... For some reason the gloss from the varnish on the water is completely gone in the pictures?
Once more of the fleet is complete I'll try to take shots in more controlled/moderate light.
One batch down, on to the next ones.