Hello, I'm new here and was not sure about registering earlier since most of the MOCs on here were enormous and dwarfed anything I have ever built, but since you appear to be in need of more small/medium sets for this project, I thought I might be able to offer a suggestion or two.
Notably, I think the Pirates theme in general could use some more small ships, bigger than the rowboats but not as large as their ships which use the big hull pieces. The only one like these in the Pirates theme was the ship included in the Imperial Trading Post, and I do wonder why no more were designed. I am putting my best one out here as a possible midsized set in the new subtheme.
Set Name: Stealth Runner
Category: 4
Faction: The Smugglers
Description: A small, fast ship with fore-and-aft sails and light weapons.
Main Elements / Play Features: Two sailboat-type masts rigged with fore-and-aft sails, six swivel guns made of cylindrical pieces, lantern on stern, small steering wheel for helm. Hull made out of basic bricks and sloped pieces.
Minifigures: 3 -3 Smugglers (Pirates), one with a captain's hat or tricorn.
Accessories: 2 cutlasses, 2 pistols, 1 musket, treasure chest and barrels for cargo.
This would be a small, fast, and maneuverable ship used by the Smugglers to run illicit goods in and out of Port Brickhaven quickly and quietly without alerting the Haven Guards. I built the ship as a pirate raider, hence the skull motif which will have to be replaced when the new design aesthetics for the Smugglers are decided on.