Help with treatment for a control room wannabe

I have a room, a finished half basement, that I want to use as a control room. The problem I have is that it still has to be sort of multi-use. I use the room as an office where I work in a non-audio capacity, and I also have another space eating hobby in the form of model trains for which this room is also the only possibility. My goal is to have the room sound as good as possible. I'm not worried about isolation as I just can't afford to have the room out of commission for my work long enough to do the work that would need to be done, and my neighbors haven't complained yet :) I'm not recording full bands, just recording an instrument at a time, and mostly guitars, vocals, and bass (DI). Drums are done with an electronic kit. Like I said, my neighbors haven't complained, and if they do, I'll just complain right back about their Karaoke parties that run until the wee hours of the morning. Eventually, I might build a tracking room in the garage, if isolation becomes necessary. The room is half sunk (half of it is below ground, the other half above), and there is a 7 1/4 inch ledge running along the outside wall. The usable floor dimensions (if you were to remove the train table) are 11'7" x 16'6 1/2". The air space of the upper half of the room is 12'2 1/4" x 17' 1 1/4". There is a window on one end of the room (above the train table) and at the other end of the room, there is an access hatch to the crawlspace below the house. The room is carpeted, and has a vertical dimension of 7'9". In the pics below, you can see the room without treatment, and the room with what I've come up with for treatment. The absorbers on the front and back of the room would be made acording to some plans I saw here somewhere - can't find the link at the moment - with 4" of OC 703 covered with fabric of some type, surrounded by a frame made of 1x8, though I'm wondering if 1x6 is better or worse. They would have a cloth back. The ones in the back of the room would be 6 feet tall plus a couple inches for wheels, as they need to be mobile so I can get to the train. The two corner traps would be the height of the room (7'9"), and the one in the center would cover the majority ofthe distance between the ceiling and the top of the crawlspace access. First, are the ones at the back of the room going to be effective? Or am I just plain screwed? Second, I've read that bass traps in the corners should be tight up against the wall - the way I have them now, they won't be as effective, correct? Third, this would mean I'd have to extend the front left trap over the ledge to the upper part of the wall, right? The sketchup file is accurate to an inch here and there. The stairs are stairs, not a ramp, and there is a door at the top of the stairs. It's not shown because I had all sorts of trouble with getting the "stairs" to work right without destroying the other items around it. Here's a link to the sketchup file. I can't get it small enough. http://laughingd.com/stuff/basement.zip

Mark - I like your idea but I would tend to go for a constructed front and a movable rear. The front geometry of a listening space is very important IMHO. Here's your room with that factor added. cheers john

John, thanks for the input. The problem with the constructed front is that I then have to learn how to build with angles. I've planned on doing that anyway :) A couple of questions. First, the constructed solution would make a huge difference? I guess, obviously, you think it would or you wouldn't have taken the time to present it. I've been reading Kendale's thread, and it looks like so much physical labor :) I'm such a wuss when it comes to physical labor. Years piloting a keyboard did it to me - I think I've forgotten how to use muscles that do anything more than punch keys. Second, on the sides of the listening position, looks like you've put Helmoltz resonators, correct? Are they likely to be an improvement over all the absorbers I had in my original? Again, thanks for the input. I'll likely do something close to your design, despite the fact that I'd have to likely get out of my chair to do it.