A bit of lateral thinking here.
One of the ships could be a derelict boat. You could buy any of a number of period hulls. Then design and scale the supersturcture to 'G' scale.
A couple of photographs from the period would show you how the deckhouses were arranged.
By scaling I mean, for example a schooner type hull could be used to make a 1/10 scale fishing boat with a single mast, or a 1/24 scale two masted schoooner.
As the model would be of a derelict you can age her a lot. You won.t need to worry about deck fittings as they would have been stripped, you only need to make holes where the missing item was and weather a bit more lightly.
If she is a sailing vessel you won't need to worry about rigging, just geve her a mast and I assume the spars would soon be salvaged as well.
If you really wanted to go all out you could scratch buid a hull, and if the planks don't fit well that would also work as the caulking would eventually rot away, and you could also have some missing planks.
This would also be in period as wooden sailing boats were still common, but were already being phased out for steel and diesel.
Like I said, off the wall thinking.