The discussion with @CarloArmato and @renzor51 in the “Simple slaughter” build thread gave me this idea to a 9 lasers, no ghost heat build. HSL+2 for ML means that we discount 2 MLs when checking for ghost heat. So... 6 MPLs, 1ERSL (syncs well with MPL), and 2 MLs in the arms should not generate ghost heat. BEHOLD the 50 points* pinpoint alpha of the 50 tons mech! *rounded up to the nearest integer. Note: theory crafted, to be tested. Heat should be OK for a few alphas, then if in a brawl use the MPL+ERSL only and add the arms ML as heat allows.
Unluckily this build should trigger ghost regardless of your workaround. If I remember correctly, HSL quirk bonus work only when all weapons fired are similar: if a weapon differs from the quirk, it will trigger ghost heat (for instance, RFL-IIC has a +2 LPL HSL, but you still can't fire 2xLPL + 2xHLL simultaneously).
I'm not sure about that. For instance, the ERPPC quirk on Marauder 2 4L works with ERPPC + Gauss combo
Medium pulse lasers aren't included in that HSL. It only applies to ML's and ERML's, which I know from experience that you can mix on this chassis under the quirk.