Strongman is not a Heavy skill and as most of the personal traits that give a weapon profiency it creates all sorts of problems, while at the same time creating opportunities for more varied builds.
The way to use Strongman is with a character who is not a Heavy, one of the more popular choices being an Assault/Sniper. The problem then is that the +30% accuracy (which was always there until someone spotted it one day) combined with Sniper armor and Marksman made the Hel 2 Cannon into the best SR in the game. I have my doubts as to whether the 20/20/-20 approach will work… Personally I’m leaning towards taking out the damage buffs from the personal traits entirely…
I wrote a guide a while back about classes. It was before Danforth, so things have changed, but you can take a look if you are interested: