I don't believe that baffles & tuning plates by themselves is going to help much with fuel efficiency. They do, however, solve the problem of uneven temps. For fuel efficiency, you need to look at sealing any leaks around your SFB & MC. I use loosely rolled HD foil & get pretty good results.
I use the inverted charcoal tray as a baffle. I have not drilled holes in it as some have done. I lay the cooking grates that came with the SFB across the bottom of the MC & put the inverted tray on top of them. The curve of the tray will matchup with the curve of the SFB opening. If I butt the tray right up against the SFB opening & close it off completely, I actually get 20-25 degree higher temps on the opposite side of the MC. I have a long shaft screwdriver that I keep at my grill. I use the screwdriver to slide the tray from side to side to dial in balanced temps. By leaving a small gap on the SFB side, I can get temps within 10 degrees. This setup also gives me the option to slide the tray all the way to the left & create a hot zone on the SFB side when I want. This is good for crisping the skin on BBCs or bacon on ABTs.
This method works for me & my CG. Of course my CG may react slightly different from yours. Your weather conditions may be vastly different from mine. So as always, YMMV.