EDITED 14.01.19: Deleted variants that were too light on ammo, added Blagg's variant to OP. Weapon Groups: 1: 2x MLas 2: TAG 3: 3x LRM10 alpha It plays like a smaller, lighter, faster CPLT-C4 (I cite Blagg Zear's "Heavy Missile Support" as the exemplar of that chassis, and missile boats in general), sacrificing 10 tubes, AMS and some armor for a speed boost, a bit more self-defense weaponry and a much less conspicuous target profile (no "ears" to shoot off). If you like this build, check out Aylek's GRF-1S "Missile Mayhem;" the Griffin can effectively mount the same loadout, while cramming in one more MLas(!) Blagg chimed in with a "Faster, Cooler, Looser" alternate: Option: Utilize the stock XL275 in lieu of the XL280 for cost savings. Since this is the less expensive option, I would suggest trying it without Artemis first; if you're not happy with the results you can give the increased missile precision a go.
I've been using the same build. I tend to hang out behind an atlas or other assaults as I'm quite helpless against lights or other close brawlers. Despite this, the 3 LRM10's put out great damage without too much heat at all. I was running out of ammo way early with 900, I upped it to 1080, and I usually can last until the end of a match. I think that amount of ammo is necessary. I'm using exactly your ammo variant. I was working on a build using 2 ERLL to up the direct damage capability, but its difficult to get it to work out.
Looks good to me but 720 is not enough. Must have 1080 at least just like every other lrm boat should have. I find the spread of lrm10.launchers fine so can use without artemis. Ammunition is more important. Also 10heatsinks are too few to cool fast enough for a constant stream. Try this here:
After playing this build for awhile, I agree with Blagg's observation. Although I find that I get more kills with artemis with the spread so crazy tight, I've been getting more damage with two extra heat sinks and an extra ton of ammo. I really like this build. Great mobility and pretty good firepower. You need support though.
PooHH--here's my take on your 2x ERLLas request: I had to drop Artemis, 2 tons of ammo and... more armor than I'm comfortable with, truth be told, to get them in there; you just can't have everything on a medium chassis. Also, this puppy runs HOT... you bump up to 50% heat efficiency once your missile payload is spent though (even better with conventional LLas in lieu of ER), so I think it's workable with good fire discipline. At this point it's no longer a missile boat though... it's a somewhat fragile sniper platform that might catch people off guard with a surprisingly decent LRM punch. Let me know if it works for you, or if you have any improvements... might just give it a spin myself at some point!