Ok, here's a revised plan using Trench Fighter:
1: Gun Chemist: Point-Blank Shot and Precise Shot.
2: Gun Chemist: Alchemist Discovery: Frost Bullet.
3: Musketeer Cavalier: Rapid Reload and Friendly Fire Maneuvers.
4: Trench Fighter: Amateur Gunslinger: Quick Clear.
5: Gun Chemist: Dodge.
6: Gun Chemist: Discovery: Tanglefoot Bullet.
7: Trench Fighter: Rapid Shot and Mobility.
8: Trench Fighter
9: Gun Chemist: Manyshot.
10: Phantom Thief: Weapon Finesse.
11: Phantom Thief: Shot on the Run and Rogue Talent: Combat Swipe: Improved Steal.
12: Gun Chemist: Discovery: Pheromones.
1: Gun Chemist: Point-Blank Shot and Precise Shot.
2: Gun Chemist: Alchemist Discovery: Frost Bullet.
3: Musketeer Cavalier: Rapid Reload and Friendly Fire Maneuvers.
4: Trench Fighter: Amateur Gunslinger: Quick Clear.
5: Gun Chemist: Dodge.
6: Gun Chemist: Discovery: Tanglefoot Bullet.
7: Trench Fighter: Rapid Shot and Mobility.
8: Trench Fighter
9: Gun Chemist: Manyshot.
10: Phantom Thief: Weapon Finesse.
11: Phantom Thief: Shot on the Run and Rogue Talent: Combat Swipe: Improved Steal.
12: Gun Chemist: Discovery: Pheromones.