I%u2019m not sure that%u2019s entirely accurate. I have 100 ton fighters with .1 deployment time, and they take two crew, even though any ship with an engine, a weapon, and a fire control should require 3 crew even with very small components.
I have designed 500 ton, engineless, missile defense stations before with zero crew. Even with something like 30x box launchers, a MFC, and a set of passive and active sensors, these stations still had zero crew. I deleted the DB file but I might try and recreate these again soon.
EDIT: See missile defense station below:
Ragnar class Orbital Weapon Platform 497 tons 0 Crew 27.1 BP TCS 10 TH 0 EM 0
1 km/s Armour 1-5 Shields 0-0 HTK 0 Sensors 0/0/0/0 DCR 0 PPV 3.4
Maint Life 10.34 Years MSP 40 AFR 99% IFR 1.4% 1YR 1 5YR 10 Max Repair 1.0 MSP
Magazine 34
Lieutenant Commander Control Rating 1
Intended Deployment Time: 3 months Morale Check Required
Size 1 Box Launcher (32) Missile Size: 1 Hangar Reload 50 minutes MF Reload 8 hours
Size 2.0 Box Launcher (1) Missile Size: 2.0 Hangar Reload 70 minutes MF Reload 11 hours
Missile Fire Control FC11-R100 (1) Range 11.7m km Resolution 100
Missile Fire Control FC20-R500 (1) Range 20m km Resolution 500
Missile Fire Control FC2-R1 (1) Range 2.5m km Resolution 1
Interplanetary Ballistic Missile (1) Speed: 100 km/s End: 7.4d Range: 64.6m km WH: 0 Size: 2.000 TH: 0/0/0
Spy Satellite (EM) (1) Speed: 0 km/s End: 0m Range: 0m km WH: 0 Size: 1 TH: 0/0/0
Spy Satellite (Thermal) (1) Speed: 0 km/s End: 0m Range: 0m km WH: 0 Size: 1 TH: 0/0/0
Orbital Launch Ballistic Missile (30) Speed: 200 km/s End: 47.4m Range: 0.6m km WH: 1 Size: 1.000 TH: 1/0/0
Active Search Sensor AS1-R1 (1) GPS 1 Range 1.3m km MCR 113.5k km Resolution 1
Active Search Sensor AS5-R100 (1) GPS 100 Range 5.9m km Resolution 100
Active Search Sensor AS10-R500 (1) GPS 500 Range 10m km Resolution 500
EM Sensor EM0.1-0.5 (1) Sensitivity 0.5 Detect Sig Strength 1000: 5.6m km
Thermal Sensor TH0.1-0.5 (1) Sensitivity 0.5 Detect Sig Strength 1000: 5.6m km
Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s
This design is classed as a Fighter for production, combat and planetary interaction