On the Lightnings:
You could get away with smaller sensors, I'm not sure what the ones you have mounted weigh, but even with an Active Strength of 10 and an EM Strength of 5 you could easily get away with a 5 Ton sensor @ Resolution 1 for the purposes of Target Acquisition when using a beam weapon. Right now your Active Sensors have 20x the range of your guns AND your FCS. Range is too short, even for carrier-based craft. You want about 1 billion km total range. Remember that for the purposes of A to B transit, divided your total range by two, but for combat divided it by three as you have A to B, fight at B, (hopefully) return to A.
You don't have to divide it equally mind you... 0.3 Billion for transit to the OpFor, 0.1 Billion for Combat Maneuvers, and another 0.3 Billion for RTB gives you 0.7 billion km. 1 Billion is nice to have though... especially when using only Fighter Sized Tanks for fuel. Each tank confers 1 HTK, despite it saying 0 HTK, as the tank itself is destroyed when hit so it is it's own HTK. Anything with 0 HTK has 1 HTK, anything with 1 HTK has 2, etc. Using only Fighter-Sized tanks makes it harder for the enemy to chew through your fuel reserves if they score internal hits. it is expensive though...
I'd go with the Lightning 01, bring it up to 0.7 ~ 0.1 Billion km range. Drop a layer of armor if you have to. You should need 50,000 litres of fuel to get that range, and you already have 33,000 of those so you just need to fit 17,000 more somehow. If you can reduce the weight of the Active Sensors, that'd do nicely... might even free up some crew while you're at it if the senor is over 10 Tons. Those Corvettes are ridonkulously fast for Magento-Plasma BTW, so well done to you there! All they really need is a little more range, and arguably they are too tough for their mission profile. I like the 04 the best, just add 44,000 litres of fuel and good to go, but I think the 01 is the best choice out of the bunch since armor is good to have. I'd be tempted to halve that though... but I run my ships with really light armor, like suicide levels of thin armor... so maybe don't do what I do, eh?