Thx for the feedback! I should mention that I actually talked with one of my contacts at Substance 3d specifically about this. I am able to use multiple UDIMs, but keep as a single texture set. This way, I can paint over the seams of 14 hand-defined UV chunks, each with 4k baseColor maps with baked lighting. This enables me to re-project higher, 8K images from the drone and handheld Nikon footage, to make the ground texture that more detailed. I added to my previous RCP navigation->industry standard feedback. :) Fingers crossed!

Thank you for the quick reply! Regarding the UDIM workflow, do you have any suggestions for an alternative approach? I was told that the developers mentioned it would be no problem with multiple 4K maps, which these large environments need to ensure crisp textures (at least up close and within a 50-100 feet radius). I will look into the first 2 options presented immediately. Option 3 is good to be aware of, but I'd need to work with a programmer familiar enough to execute it. Side note while I have your attention - is there any way in RCP to combine camera Orbit, Dolly and Pan into a single command assessable via Option+Right/Middle/Left mouse click, exactly similar to how Maya works? This would be a huge improvement for quick navigation. :)