- Without an Active Sensor, your Stealth Ship cannot acquire a target to shoot at. The active sensor feeds the targeting data into the Beam FCS, passive sensors, like EM and TH cannot do that. Also, that laser is freakin' yuuuge, but fires really slowly. 5 second reload is the gold standard, but those big ol' honkin' 35cm ones are great if all you want to do is zoom in, blast the frakk outta the target and zoom away. However, 7,500~ km/s is kinda slow for boom and zoom or kiting at this tech, although it can work. 9,000+ is much better, but you'll lose a lot in range... and I mean a lot. 7-8k km/s is more than fine if you want to "stand and deliver", but that's only really useful in conjunction with missile warships or by utilizing specific tactics.
- Those passive are stupid big, I'd consider trimming them back. You only need as much reactor as you have capacitor. Three Capacitor 3 Lasers, regardless of size, will use 9 power. so the reactor only needs to put out 9 power. Power Output of 1 is enough to fill 1 Capacitor every 5s. So if your laser needs 15 power, but only has a Capacitor of 3, it's going to take 25 seconds to fire and require 3 Power Output in total. At Capacitor 5, it'll fire every 15 seconds and require a total Power Output of 5. Two such lasers would need 10 Power Output, and so on and so forth. 900,000 Litres for 31 billion range is a little steep, but only a little. I'd recommend playing around with engine size and boost, you might gain some extra tonnage, range AND speed all at once.
- Cloak requires more of a tech investment if you want to make combat ships with it. Cloak has overall been kinda nerfed with the new sensor model in C#, moreso than Thermal Reduction which if anything got a buff on account of the new engine mechanics. Cloak reduces your Target Cross Section (TCS) to a certain percentage of it's original Mass. For example a 10,000 Ton ship with 75% Reduction Cloak will yield a TCS equal to a ship of 2,500 Tons. On a 1,000 ton ship, the same 75% yields a craft equal top 250 Tons. So instead of a Resolution 200 Sensor seeing your 10,000 Ton ship, you would need a Resolution 25 Sensor instead. The new active sensor model, however, makes smaller sensors much more effective... so cloak is less useful than it was before. At early tech it is best used on specialized scouts or missile warships. Later on it becomes viable on very small carriers and later still it becomes useful on beam warships.
- That thermal reduction isn't helping you at all. It kinda stacks, two engines with 50% Thermal Reduction will be half as hot as two engines w/o it. However, the effects are not cumulative; i.e. two 50% Reductions resulting in a 25% Reduction. Your armor is decent enough, and that cloaking device will make you appear about as big as a Fast Attack Craft, which are ships between 501 and 1,000 Tons. FACs, as they are called, don't need a Bridge btw. That Cloak will make your ship harder to find on actives for sure, but those engines are so damn hot it really won't matter. 0.80x Power on engines gives a LOT of fuel economy for only a little loss of power, at least in VB6; the engine model is different in C#, but I'm fairly certain the gains are still worth it. You could probably cut back on the Engineering Spaces and / or Maintenance Storage. Your weapons have a 1% failure rate, so don't trim MSP too much, with a 750 Max Repair you're already looking at 1,500 MSP to repair a battle damaged engine. However, 16 Engineering Spaces is probably overkill. You could definitely get away with EM /TH of 20-60, but 80 is quite good... generous and tonnage consuming, but good.
- I would also consider more weapons... possibly railguns or turreted gauss for Point Defense against missiles.