So, I trimmed my library to 25k songs, then uploaded to the cloud using iTunes match. When iTunes match said that I had 25k songs uploaded in the cloud, I added the rest back into iTunes. It works, and iTunes match continues to work, but it gives a prompt saying there is 25k limit so these songs, and future added songs, won't be added to iTunes. It even gives a check box saying don't show this message again. So it is possible!