While waiting for the patch to finish, I theorycrafted this build for the 5J. It should work well as a fast moving sniper able to unload and then relocate quickly. 20DHS give it a respectable heat dissipation speed. Would make an ideal CW 'mech, able to quickly move around the larger maps and provide long range support.
5/5, It works pretty well IF you can manage the heat in longer fights, and stay out of trouble. Almost the same build, removed 2 DHS and a bit of leg armor für double AMS + Ammo and 2 JJ