i will increase the grid amounts, for resizing, could you take it into photoshop or gimp to crop it?
I think that can work, my only concern with that is retaining the image resolution. If it outputs at 4k and I have to crop it down to get the right shape it won't be 4k anymore but it would be enough probably. Also, I'm making videos more than images (see https://www.reddit.com/r/FlowScape/comments/aq42un/swamp_battle_map/ !), which I think is practically the same issue.