I've figured out the issue is with the content.xml of the DLC. Some items need to be changed to "false". I've noticed there's a collision issue in the race_col_sol.ybn. The pit entrance and exit has no collision. Part of the area also still has the LOD for the default map chunk but I'm still testing if items in the content.xml file need to be changed so it loads properly.
I installed all 3 MLO, but the way to isolate PDM specifically is by handpicking the dt1_22 items in the download and replacing the vanilla ones in OpenIV. Then you need to delete all the ydd related to the destroyed carshowroom in vanilla GTA also.