Any way to edit trs2019's default terrain "PBR Grid (2.0)" texture?

[BraselC5048]

If I'm going to be using trs2019, I'm going to be spending my time looking at a grid, and I can't stand the default one. (PBR grid (2.0). It would be easy enough to edit it to use the old grid texture, except for the built-in and payware combination. I can import it into trs2012, edit it and get rid of the permissions section, but I can't delete it in trs2019 and import the edited version or or overwrite it.
Is there any way to edit this, or would I be stuck with the hideous default grid if I upgrade?
Thanks.