As much as I'd like to see these pirate/terrorist factions get more custom designed ships of their own, I'm a huge huge fan of unlawfuls using captured/subverted ships of their enemies. Modified Rheinland gunboats and bombers for example, or pretty much any freighter/transport (some converted to combat duty as shipping raiders).
The Red Hessians are a sizeable faction with their own ship production capabilities, but it is a certainty that an organization like theirs would make use of captured and customized ships in significant numbers.
"To gain a hundred victories in a hundred battles is not the highest excellence;
to subjugate the enemy's army without doing battle is the highest of excellence."