Re: Pre exhaust routine
For chest pre-exhaust, why not just do db flies on the bench you're using for yer bench press? That way you don't have to leave the bench? Or just do db chest press with the fly's and have two sets of weights out by your bench at all times, usually a good sign that the bench is being used by someone.
Also, could do military style push ups (the ones with your elbows tucked in - focuses more on triceps) and then do bench press?
12 weeks sounds like a long time to train using pre-exhaust technique, it can take it out of you and IMO not ideal for all lifts. I'd listen to your body and watch out for any niggles.
"Fatigue makes cowards of us all" - Vince Lombardi