It isn't that hard. Lou is the abbreviation. Just Lou. No LA, ULL, UL-L, UL-Laf, UL-Laffy or anything else
Lou is the same as Arkansas, Ark, Mississippi, Ole Miss, or just Miss, Alabama, Bama, Tennessee, Tenn, Missouri, Mizzou, Nebraska, Neb
None of these schools use the U in front, and it is permissible.
I would prefer Louis but that sounds like Louisville. Just Lou