had some time to play with my wheels today and see if I can find the solution. Bought some 3mm spacers and this is enough to clear the calipers... However, there is only like 0.5mm clearance. I would feel more comfortable with at least 1mm to cover for any expansion of the caliper on track days. In reality it shouldn't expand but 0.5mm is cutting it too fine.
So got in touch with the shop and asked them for 4mm and they said they only do a 5mm spacer when custom made, as I want it to be hubcentric with 56.1mm bore to fit onto the hub and 75mm on the hub ring to center the Enkei.
After worrying if a 17x9 ET38 (ET43-5mm spacer) would fit with 245/40 17 tyres, I went outside to see. With my current setup, the new Enkeis with spacers would poke out more 9mm. I think I got around 20mm to play up front with so thats good news. I may have to run more camber in the rear though but thats easily achievable as I have adjustable lower arms.
Looking around on the web, lots of Americans are running 17x9 ET 38 with 245/40 and have zero rubbing issues. So that has given me the confidence to go ahead with the 5mm spacers.
So the plan of work is 5mm spacers and extended wheel studs just to fit some track days wheels....

They do look good though!!!
here are the pics:
Eyeballing it, I got plenty to poke out 9mm more than currently.
This is what I will have made up in 1pc. Currently its just a hubring ontop on the spacer.