I am currently training
Monday Chest shoulders tris
Wed or Thurs - Back Bis Traps Forearms

I dont train legs, they are already big enough.
(body_insp.tripod.com)
I am trying to gain lean mass, yet if I eat a hyper caloric diet, especially since Im not active on the other days, I assume Ill gain quite a bit of fat. How can I work around this EFFECTIVELY?

PS> I feel its more effective to train chest shoulders and tris on one day because they all get sore anyway, so might as well train em full throttle. Thats the big issue.

Tell me, diet wise and training wise, what can I do?