If you have halfway decent missile and sensor tech, missile fighters paired with a spotting platform (PDC with a giant sensor, ship with a giant sensor and an engine, &c.) are going to be your most efficient use of resources, but if you're dead-set on a laser FAC, here's a design at that TL, except for the armor density because I just drew it up in my current campaign.
Iron Duke class Fast Attack Craft 1,000 tons 42 Crew 497.5 BP TCS 20 TH 75 EM 0
3750 km/s Armour 1-8 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 0 PPV 8
Maint Life 5.52 Years MSP 155 AFR 16% IFR 0.2% 1YR 9 5YR 129 Max Repair 180 MSP
Intended Deployment Time: 6 months Spare Berths 2
75 EP Ion Drive (1) Power 75 Fuel Use 116.17% Signature 75 Exp 12%
Fuel Capacity 40,000 Litres Range 6.2 billion km (19 days at full power)
25cm C4 Ultraviolet Laser (1) Range 240,000km TS: 10000 km/s Power 16-4 RM 4 ROF 20 16 16 16 16 12 10 9 8 7 6
Fire Control S01 120-10000 (1) Max Range: 240,000 km TS: 10000 km/s 96 92 88 83 79 75 71 67 62 58
Stellarator Fusion Reactor Technology PB-1 (1) Total Power Output 4.2 Armour 0 Exp 5%
Active Search Sensor MR70-R16 (1) GPS 2560 Range 70.4m km Resolution 16
It's not perfectly optimized, of course, but that's about what you're going to get. It's a perfect example of why with the new drive model E/KW FACs don't really become useful until higher TLs; as it is, they're large enough to show up on sensors beyond their own engagement range (unlike missile fighters), don't have the durability (or speed) to make a run through fire (unlike larger vessels), and don't have enough damage to do much if they manage to survive long enough to fire (unlike larger vessels).
OTOH, a swarm of FACs loaded with box launchers (and half-decent missiles) based from planetary facilities can be an effective deterrent measure against lighter enemy forces. But again, if you're going to do that, it's cheaper and more effective to do it with fighters. :/