My version of axle support plan B

If a shop isn't available that will do it, the same basic idea should work for the torsion axle but you would need probably a 1/4 inch thick or better short piece of 3 inch steel angle to protect the torsion axle tube from getting pushed in by the bottle jack. If the axle is still crowned you could place the jack at the frame attach point on the side that shows negative camber. If its flat in the middle then place it in the middle. Not for the faint of heart, but better than just cranking down on the 1/2 inch bolt I think. Take your time, release and measure, and please be careful. 

One thing though, an axle that is de-cambered is bent. If the steel hadn't reached its yield point it would have returned to its original shape once the stress was removed (elastic deformation). Once the yield stress in exceeded it will no longer return to its previous shape (plastic deformation). It will take on a permanent strain/bend.  It will also become work hardened and more brittle.The next time it is over loaded it will take more stress to bend it further.  The good thing here is that we're taking about pretty small deflection angles because the tube is so stiff so its not like these things are getting bent into pretzels. 

Here is an interesting video discussing this and showing one way to straighten/recamber an axle. 

I could maybe see trying to do this at home with a high capacity jack if a safe way could be found to cradle the axle and chains. 

Should be about 32 fl lb max dry or 24 lubricated assuming a standard low carbon bolt and coarse threads. That ought to  develop around 5000 lbs of force which the bolt can take but I doubt your support assembly can. So be careful not to bend something (like your frame rail )

If you can apply enough force (needs to be around that 5000 lb range) then that ought to bend the axle end back and remove the negative camber but don't leave that force on it, you wouldn't have any capacity left in the reinforcement assembly to handle any future bumps. 

I never asked my local shop if they could straighten my axle because it wasn't bent, but I know it can be done. toyanvil just had his done. So you might want to try calling around some other places to see if they'd be willing to give it a try. 

Good luck!