cut the map up in photoshop into less than 8k but evenly sized sectors. make a plane in max with the full map (low res) applied to it at the correct scale over the top of your main object. cut this object up into the same evenly sized sectors as the map, uv to fit and apply the material for each sector to it. take your object, cut it up, and take the mapping from the plane underneath it.
in photoshop you can still work on the fullres 30k+ map and save out sectors that you’ve updated as needed.
You can do this with unwrapped maps and other objects pretty easily too.