Boot modifying

The fitter you saw is by far the most knowledgeable, experienced and best equipped boot fitter in the UK.

DIY is not an option because of the amount of work involved and the specialist tools and skills required.

You say your knees are around 7" in front of your toes, that is a massive amount they should be roughly over your big toes. Your "very bow'ed lower legs" may be bowed beyond what any boot's cuff alignment mechanism can accommodate. The back of the boot would have to be flared out to accommodate your large calves and you might need a thinner liner. Your "extreme hyper mobile" ankles would need to be controlled by a stiff boot, there are safety issues with putting novices in stiff boots. There may also be other issues, you haven't told us anything about the size, shape and volume of your feet.

There is no point in having a biomechanical analysis as you've already had one, you gave the results above. It looks like the range of movement in your ankles, the circumference of your calves and the amount of bow in your lower legs are all well outside the range required for skiing. Did you suffer from Blount's disease as a child?

http://www.daleboot.com/87.html

mad to order ..they say they are opening in the UK in October

The Daleboot is sometimes recommended for people with problem feet, very high arches, very high insteps etc. The OP didn't mention anything about his feet, his main problems seem to be hypermobile ankles and tibia vara.

The fitter the OP visited is only a short distance from a shop that used to sell Daleboots, when he was of the opinion that Daleboots would be the best option he referred the customer to them. As they were still trading when the OP went for his fitting I would have thought he would have referred the OP to them if he thought they would be suitable.

At about $800 you would want to be absolutely certain they were going to work before getting a pair.