First, the Penetrator is a great mech so good choice! I like the rest of your force alot, great choices. The only thing I would consider is dropping the Enfield and/or Bushwacker for something more mobile/jump capable... Combined with the Stealth and the Enforcer III (even the Falconer) two other fast jump capable mechs could really move around the board at high speeds over any kind of terrain and really help you split forces up.... Things like:
Hellspawn 6/9/6 or Griffin 5/8/5 for long range
Shadow Hawk 5/8/5 or Wolverine 5/8/5/ for balanced
Nightsky 6/9/6 for brawler
Phoenix Hawk, Firestarter Omni too...