Shields can force the main fighting to be within 5 light seconds anyways.
I don't see the problem.
And how well does those shields work against particle beams ( which retain full damage out to max range ) or against mesons ( which ignore shields )?
If the particle beams are on the attack? They cap out at 1.2mkm. They can afford to force you in closer by having a vastly cheaper FC and cheaper weaponry, in tonnage terms.
If the Particle beam ship is the one needing to weather the storm to get its kill, then with you can match their 15.5kton investment into destruction on a smaller investment of just 8200 tons with an 8x FC getting you 7300 tons to spend on shielding if your need to to force them closer. That lets a 25 damage 20 RoF 800 ton particle beam, with 10 on one ship, output 250 damage at 65% odds at 700kkm, for a sustained 8.125 damage per second, and a whopping 146 shields, for the same tonnage budget.
Do note that I've ignored the cost of carrying enough MSP to ever manage a single repair of the only firecontrol on the ship, which swings things further towards the inferior tech shield heavy ship. 80,000 MSP costs you quite a bit of tonnage, its just far too messy to work out in excel.
So, you get 4x36hs shields. Which means you have 1440 hp base, at 189.7% strength for 2732hp more shielding than them, and 4.8hp/sec regen. This lets you sustain the abuse indefinitely beyond 1.1mkm, or last for 15.595 minutes at 700kkm over which you can do 11500 damage with strength 25 hits.
If they could kite you to death now, then they still can, with a narrow 300,000 window to do it in where you cannot respond. If you can get the closure to 1000km/s, you can close that gap in just 300 seconds, 5 minutes, you'll survive 15+.
Mesons get to play with ranges up to 10.08mkm, you are gonna get a little chewed up on the way in. Have HTK to spare. Spend your excess, if any, on armor. To have that range, they'll need an FC of at least 10.08mkm, a multiplier of 58, for an FC tonnage of 1450, and 10 weapons, at 1250 tons, it costs them 13950 tons.
Now, one would think that mesons bypassing shields and armor become king. Except, in c# they don't entirely bypass armor, they may be stopped by it, you can weather this storm, somewhat. 7% chance to not penetrate at maximum tech, 93% chance they do penetrate per layer of armor. You can make a max tech warship at around 35ktons easily enough. Putting 6 layers of armor, 6 shields, 2 16HS x2.15 engines, and 14 Large fuel + 1 Normal gives a 35kt warship that can do 70kkm/s over 20bkm and still have 22ktons for mission package. Plenty of headroom to load the 15.5kton weapons package above.
So lets drop two engine tiers to plasma core engines, .16 fuel, and drop two tiers in armor. 35ktons, 9 45hs x3.0 engines, and 53 Normal Fuel tanks, and I get a warship that can do 106.5kkms over 9.5bkm 10 particle beams as above. 6 layers of armor leaves just enough mission package to carry adequate MSP and a simple sensor, very short endurance. We've a closure of 36kkm/s if they attempt to run. A lucky strike could send us packing, we can lose 2 engines before they can close in on us.
We can close the range in 260 seconds, or 7 firing cycles before we can retaliate. So I will assume they get shots every 1340kkm of range closed in, starting from 1000kkm outwards, so the first shot as closing would occur at 10.076mkm. They have a 93% chance to penetrate armor per layer and we have 6 layers, so they have a 64.7% chance of getting an internal hit per actual hit, they've got 10 weapons. The first salvo at 9.04mkm nets 0.667 hits, 7.7mkm nets 1.53 hits, 6.36 nets 2.39, 5.02 -> 3.24, 3.68 -> 4.1, 2.34 -> 4.97, 1 -> 5.83, sum total of 22.7 hits, call it 23.
We have 207HTk in just engines, comprising 69.9% of all hits. 50HTk in fuel, 44 HTK in crew, 12 in engineering. In DAC, 415-558 is particle beams, 562-565 is fire control, 610 is search sensor, 674-682 are reactors. Those comprise just 155, out of a total of 686, or 77.4% of internal hits are going to be absorbed by systems not critical to killing the opponent - though engines can really only afford one loss.
She's short legged, but can win her fight by taking 65% engine/fuel, can't go hunting, but if they come to her...
Can you overcome a min-maxed warship on the same tonnage that has tech advantage? Probably not. Can you build a tech disadvantaged warship to kill an advantaged warship? Absolutely. Can two ships of equal tech deal with their shortcomings? Certainly.
Only way the Meson holds its range advantage for same tech, is equal or greater investment into engines, or lesser tonnage. Both require you decrease weaponry, c# imposes a penalty to having few rapidly firing weapons, that 2% failure will bite you. Over 34 shots, its 50/50 that a weapon fails. The Meson wants its range, it needs to splurge on an FC, that hands the speed advantage, or the quantity advantage, or the defence advantage tot he competitor.
To get that disadvantaged in a fight between equals, one of you wasn't teching at all, or the other was handed the advantage as a handicap.
I still don't see this as the insurmountable task its been made to be.
See attached for the particle beam/meson warships specc'ed out. Keep in mind I stacked multiple FC's to consume tonnage as if it were bigger—as if the multiplier allowed such ranges, and over stocked MSP to allow replacement of the FC, which is the biggest cost in both ships.