I dont have much experience with this but depending on your proteins size id suggest looking into DOSY type experiments for this worst case scenario youd be able to show that it went from heterogeneous pre-ligand binding to something relatively smaller. if you have access to AUC though this would be better, less material required and should be more accurate, I had a problem with a protein of unknown oligomerisation state, I found estimating the hydrodynamic radius from size exclusion and using that to analyze my AUC data gave me a definitive answer. but for nmr I guess DOSY should work quite well?

I am not professional, but I have finish my experiments for protein structure analysis with NMR by some commercial company. That's very efficient if your budget is enough.