I got it all sorted out guys.
First, I took the shelves off the front and side of the char griller. This gave me considerably more room. I turned it facing another direction, which I had previously thought it wouldn't fit this way. Now the wall closest to the fire box (still a couple feet away) has no electrical outlets, internal wiring, or anything else.
I then hung the welding blankets on all the walls (the welding blankets that I have been duct taping all around the smoker when doing cold weather cooks). They're just loosely hung, nails in the top.
I built a cement board "box" around the side fire box. What I did was took a cinder block, one of the 8 x 8 ones with a groove in the top, and put that on the cement floor. I then cut a cement board sheet in half, and stuck that half in the groove of the cinder block. I then sat 2 big, heavy, cement bricks (I think they're actually supposed to be cinder block toppers) on top of the cinder block, on the sides of the cement board. This "sandwich" holds the cement board up.
I did this on the front, back, and side of the fire box. I then laid another piece over the top of them to cover the fire box.
There is about an 8 or 9 inch gap between these pieces and the fire box, and about an 8 in gap below them to the concrete floor (they sit on 8 inch cinder blocks, which are on the concrete floor, but the cinder blocks are only 1 per side and hollow, so there is skit a lot of air space).
After that, I took 3 full sheets of cement board and put them up in front of 3 the walls.
I used the same technique, sat a couple cinder blocks on the floor, sat the cement board into the groove, sandwiched it in with the big heavy cement topper bricks.
These ones have about a 3 inch gap to the shelving and counter tops behind them, and then about 1.5 or 2 feet to the wall. They have about a 9 or 10 gap the other way, to the smoker.
I didn't put any up over the 3rd wall because it's so far away. It's about 2.5 or 3 feet away, and has a welding blanket hung over it. This also means I can access 1 of the counter tops.
I think the cement board around the fire box would have been enough. Just fur added insurance, I put a second cement board "enclosure" around the whole smoker (3 sides of it anyway, left the front so I could access it). I'm thinking it should be fine.
Next spring I want to do a more permanent installation of a custom built smoker.