3712x5120
While my model would generate a mess in these scales (not only that, would probably take a few hours), these were done by splitting the image into chunks and generating each chunk at a higher res. You'll be able to see some minor stitching in some of the images, but wow does it look nice!
This is something I will do more, perhaps make a vote for a handful of pictures each month to be upscaled to ludicrous resolutions
(ive managed to do 10K)