I'm at my wits end

I've also got a SA dog -- Luna (the basset beagle mix) -- she's angst-y anyway (I truly believe this dog would "worry" over the sun coming up in the morning if she had nothing else to vocalize about! *smile*)

I can't tell you how many crates she's gone thru -- same story as yours. 

I can't leave her the run of the house -- she is *better* when not crated but not without severe SA.  We have two other dogs (and have had various other pets during the nearly 9 years we've had Luna) -- no one else freaks -- just her.  She simply gets completely focused on "getting out" and with Luna I don't think it's so much pure SA as it is simply a complete determination NOT to be left in a small area. 

There's a fine difference/distinction there -- THINK about it.

Some dogs do **NOT** follow the typical "dogs are a den animal" thing.  I'm going to assume this was something that occurred in her first 9 months (we got her as an almost-adult).  It's not so much "crate" she hates as the fact that when she's alone and enclosed it truly looks as tho she's claustrophobic -- and I'm NOT being anthropomorphic.  She really just does NOT like close spaces  when she's alone.  If all 3 dogs are left in a one-room "kennel" (like at dog daycare/kenneling over night or at a kennel facility while we are at a theme park or something) she is FINE.  Weirdly enough this is always more of a problem here than anywhere else!

Our solution has been to leave HER loose in the bedroom while the others are crated.  At this point Charlie is also loose in the room (Charlie has had really severe eye surgery with a long period with an e-collar on and I was afraid he'd hurt himself getting caught on the e-collar) with only Tink crated. 

 this works.  Occasionally Luna gets a wild hair ... once it was when a horse fly was in the room, another time was when she heard a Fed Ex delivery made really late in the evening ... and she'll trash the bedroom a bit.  But nothing destructive.  She just snags bedding off the bed, etc.

 My point for you is to try to be creative. 

You **WILL** want to use some form of a calmative.  A dog with true SA gets SO freaked mentally they can't think calmly enough for re-training to happen.  Getting them calm enough so you can begin to desensitize them is huge.  It took getting Luna calm enough so I could evaluate her properly == that's when we figured out it wasn't true SA with her -- but more an honest discomfort at being confined in a small area.  (she gets carsick too, and does WAY better when she has an open window and can focus on her nose rather than lane changes!)

Is there a room you can dogproof??  (things that provide a chew challenge can sometimes ramp them up -- just the sound of paper tearing, fabric tearing, WOOD cracking apart -- it can be rewarding to them -- the sheer rush of "destroying" something becomes a reward)

Have you tried leaving things like antler, or a long leg bone/marrow bone/joint stuffed to keep the dog busy for a while?

It took us forever to find the solution to Luna.  For us the "key" came after we systematically examined the 'damage' she did to one crate.  This wasn't a dog throwing herself at it or trying to use brute strength.  She very systematically broke the welds on the ends of the wires on the front.  One ... after ... another.  This took her WEEKS.  She didn't try randomly -- nope ... it was one .. then the next ... she was apparently able to "build" on the weakness created when one wire would break free -- to then get the 2d. 

The fact that she would simply spend hours stressing one small wire join??  Her's wasn't just a broad hissy -- it was calculated "I will get free if I just keep working on this".  We observed her without her knowing -- her focus was pretty amazing.

I hope something in what I've said helps you at least a little.

Oh -- and one more thing.  This is again "weird" but for Luna it is significant.

 She will respect a barrier -- like a baby gate between two rooms.  It doesn't even have to be super solid. 

But a DOOR???  Panic time.  She tore thru a hollow door -- she literally peeled the veneer and then BROKE THRU the thin plywood of the bedroom door. 

Put a baby gate up and she respects it!

 Again -- we think it's that "don't confine me in a small space".  If she can SEE thru or over the barrier she's fine. 

 There are questions I would need some answers to first.

• Do you crate/contain the dog at other times thoughout the day/night also, or only when you leave?
  
• Does the dog get a great amount of activity throughout the day?. Pitts are very energetic.
• Have you practiced any separation anxiety solutions with the trainer?
• Are allowed, safe items to chew left for him when your away?