I might also have the ability to make these. I will have a go at drawing it up in a cad program once knightrous posts the details

If the OEM bar is rated to 1000kg, then it's legal to tow that much.  But I'd not try it myself.  Notice the ball weight (downforce on the towbar) is 50kg.  You want to have about 10% of towing weight on the bar so 500kg is reasonable.  
 
Anyway, a decent copy of either bar will do me just fine.  I have a 4x4 for heavy towing.
 
Cheers,

Eric, if you could design and/or make them that would be awesome.
 
I can commit right now to buying one if someone can make them or has them made. Would be nice to have a design which utilises a removable ball. The Curt unit below is from a late 80s Camry or Corolla which apparently is very close to fitting the AW11.

Mrskylighter, I can send you the designs once I get the dimensions from Knightrous, but after some discussion with the friend who I was going to build these with, I don't think I could sell them to anyone else, as if it fails I will be held liable for damages. happy to send out the drawings though, and if you take them to a towbar shop they should be able to make one in no time

That's fair enough Eric.
 
I have also found a UK company that still makes AW11 towbars. http://www.watling-towbars.co.uk/uk_cars.html
Part number is PTY61 and cost approx. 140 Pounds plus postage.
I think these might attach similar to how knightrous's one does. Using both tow hooks and the rear engine mount.
I've asked for a diagram or picture, we'll see what they come back with.

Couple more pics I found of the genuine Toyota UK one.


 

Little worried that none of those swing back to the rear engine mount for a better support structure.


 
Mine I'm not a fan of those small bolts taking a lot of the load, I want to look at upgrading it to a bigger bolt or shoulder bolt.

What modifications are you planning to do to yours knightrous? Looks pretty strong at tthe moment.

I want to upgrade the mounting bolts from the current little M12 to a much more suitable M16 in a 12.9 grade, then replace the solid brace from the bar to the rear engine mount with a 40x40x5 tube section frame with some addition braces towards each towing mount point. It might be a little over the top, but I'd rather it be a little heavier and safer then anything else.

It seems my car once had this type, as it has holes behind the bumper that appear to line up with it.