Do you mind if I join in this discussion? "Belvrog", Mark you will remember him - made a StartupScript for custom sized canvases". I can't find the post but I have the script. It was made for "ArtRage Build: 4.0.4". I altered the canvas dimensions in the script and it opens AR6. I haven't used it in a long while but I used to have it on my desktop and a simple click would open AR6 with the canvas size I had designated. I should use it again!

I don't know how, or if it's even possible to make the changes to the script for it to open in ARV which doesn't show as a choice on Select an App to open this file".