I have a decent size room 20’x33’x9’.  Due to the placement of some large columns I need to place my equipment on the long wall.  While I can achieve an equilateral triangle between seat and speakers (11’ on all sides) .... I am unable to have the front of the speakers more than 3’ from the front wall.  I am using Avantgarde Uno speakers with Pass Labs XA 60.8 amp and AR Ref 6 pre.  Sources are Lumin X1 and SME 20.  The overall sound and imaging are wonderful.  There are two problems that I can’t seem to get right.  First, the soundstage is rather narrow ... does extend beyond the speakers (have tried every off to on axis position).  Second, the image is detailed/precise but not deep ... it just sort of hangs on the wall 3’ behind the face of the speakers.  I believe that the problems are due the speakers not being far enough from the front wall but I can’t move them out more (due to the columns I mention).  Any suggestions on how I might fix these two problems?
You are experiencing a problem that is inherent in the 'stereo' design. 'In phase' information is only heard between the speakers. Sound coming from outside  the speakers appears only when it is bounced off the walls/ceiling and floor or 'out of phase' information is in the recording. In your set up you have no walls for the sound to bounce off to help create stereo width. That is one of the reasons folks like the short wall more. Depth is highly influenced  by speaker placement (5 to 6 ft is optimum as I think you know) but if it ain't in the recording, and it usually isn't, you won't hear great depth anyway. 

There are devices made to enhance stereo imaging, mostly based on introducing 'out of phase' information that might help, as there are ways of incorporating rear speakers into a two way system which can enhance the sense of sound stage. If you want to hear the effects of out of phase information (only) reverse the plus/minus connections on one speaker. Then you will hear most every thing out of phase - you will note the sound is very spacious but has no central image/focus.  

You have high quality stuff so I suspect you might not want to do this but if your up to a relatively cheap 4 speaker solution investigate the Hafler design. It actually works. But it does have a down side. Doesn't everything? :-)
Had to read the OP a couple times to make sense of it. The sound stage is narrow- but extends beyond the speakers. Okay, that is not narrow. The sound stage is detailed and precise but not deep. Well that is largely down to the recording. A lot of them are just about as you describe. Some further forward, some with greater depth front to back. They are all over the map. 

These are horns we are talking about. Not a big horn fan, you will have to ask someone who actually used your speakers to know for sure what they are capable of in this area. Also a lot of things like Townshend Podiums and Pods, Synergistic HFT, etc will make big improvements in all the areas you are looking for. Whatever you do, do NOT go multichannel, you will find yourself immersed in pure dreck.
Where are the columns that they prevent you from pulling the speakers out further?  I can’t picture what you’re talking about. 
Typically there is a "competition" between the desirable venue cues on the recording and the undesirable "small room signature" cues of the playback room. In this case apparently the wall behind the speakers is imposing its audible presence atop the venue cues on the recording, thereby limiting soundstage depth.

The earliest reflections are usually the one which most strongly convey "small room signature". On the other hand the later-arriving reflections are in effect the "carriers" of the reverberation tails which are on the recording, so imo we want to use absorption sparingly because early reflection energy becomes late reflection energy after a few bounces. My caution about not overdoing absorption isn’t universal, but is more likely to be applicable to systems with horn speakers, which do not start out with very much off-axis energy to begin with.

I suggest using a mirror up against the front wall to find out exactly where those reflections are coming from. With the mirror flush against the wall when you can see the edges of the horn from the sweet spot, the mirror is in the reflection zone. I suggest either re-directing that reflection energy (using large panels angled such that the reflection misses the sweet spot) OR diffusion (not sure which kind - I’m not an acoustician) OR aggressive absorption (very thick but not necessarily covering any larger area than necessary).

The wall behind the listening position will also be a source of relatively early reflections in this room, may well be worth treating in a similar manner.

I have other ideas about how to tip the "competition" in favor of the venue cues on the recording but they involve projects that I am commercially involved with.    

I think the best way to tackle your issues is to move the speakers around until you get the best possible soundstage and frequency response. From there you can make a choice of how much compromise you can accept.