What size filter to use for color grads on S35 anamorphic?

[Dominik Bauch]

Using anamorphic lenses on an Alexa mini with Arri LMB 4x5 mattebox.

I want to get some colored grad filters, if I get a 4x5.65 size then I have no ability to move the grad up or down, so I could use 5x5 filters via an adapter frame, now I could move the grad up or down slightly but I’m losing horizontal coverage.

With grad filters what is best practice re filter size? I don’t have access to a 6x6 matte box, will the 5x5’s cause me problems with super wide anamorphic lenses? I’m thinking 32 and down might be tricky. But having some vertical control might be preferably to full horizontal coverage on wider focal lengths.

Any advice much appreciated.

Thanks!