To follow up, here is a test shot we took with Ektar:
This is a detail from a scan. No adjustments were made.
The camera used is a Hasselblad 500 C/M with an 80mm CF lens.
It was about 3pm and overcast, but the sun poked out just before the photo was taken.
Sun was coming from the right.
The sky does look cyan here, as does the water - but that actually works for this project.
We want the colours to be exaggerated and a little unreal, so this is good.
I cannot quite tell whether the skintone is right or not.
For example, that red thing poking out of the hair if you look closely, is an ear.
Is it red because it was freezing cold, or because of the Ektar?
Not sure and will need to take more shots. But otherwise, this film is everything I hoped for.