By the way, under HG/CT rules, cargo ships dont get a lot more efficient once they get beyond a certain size.
Here is a 50kton jump-2 cargo ship designed under HG - its got the same profile as the Jacques Coeur class posted upthread ... just 5x bigger and 5x more expensive.
Ship: Bigbelly
Class: Cargo Eater
Type: Freighter
Architect: Iniigi Darashiika
Tech Level: 11
USP
AK-P52125Z-080000-60007-0 MCr 20,622.689 50 KTons
Bat Bear 3 3 1 Crew: 245
Bat 4 4 2 TL: 11
Cargo: 31,301 Crew Sections: 50 of 5 Fuel: 11,000 EP: 1,000 Agility: 1 Shipboard Security Detail: 50
Fuel Treatment: Fuel Scoops and On Board Fuel Purification
Backups: 1 x Model/5 Computer
Substitutions: Z = 50
Architects Fee: MCr 206.227 Cost in Quantity: MCr 16,498.152
Detailed Description
(High Guard Design)
HULL
50,000.000 tons standard, 700,000.000 cubic meters, Sphere Configuration
CREW
26 Officers, 219 Ratings