Max alpha with no ghost heat, both LLs are mounted on the right arm for peaking. You can alpha strike this relatively safely, but not repeatedly - you will run hot. ERMLs are possible for better medium range burns, but are much harder to manage and a clear disadvantage when enemies get within regular ML range. I use separate weapon groups for the arm lasers, CT lasers and just the LLs (arm lock off). If you get into a brawl use the arm lasers and throw in the CT lasers only on good opportunities and when heat capacity allows. -5% std laser duration is nice here, though quite insignificant in practice.
I would suggest putting one ER-ML in the arm with the Large Lasers, the ranges sink quite well, and it adds a little firepower when using your Long Range group. I also prefer to crit pad the XL engine rather than put the heatsink in the engine.
The ERML in the arm with the LLs is a good idea. Sucks that it makes the cooldowns sync up worse though. There's no need to crit pad for the engine. Engines don't take damage unless the entire torso is destroyed.
As I understand it, 3 Engine crits will kill you, thats why losing an XL side torso kills you. So the aim is to reduce the crit chances accross all torso locations and hence not die. Without the padding crits go straight to the engine. The cooldown sync is annoying but minimal.
A single PPC shot to an open torso can give 3 crits if you are unlucky. I find it increases my survivablity, i can get to red on both torsos, if I torso twist effectively and get Structure and Crit Chance Reduction nodes.