I tried to extract rpsgl models, but didn't succeed because the format is too different compared to xbox 360 rx2. Rpsgl is based on
PSGL.
Modding models isn't very simple. I have script to read X360 models in Noesis and extract it to obj, fbx or other known format. Re-importing isn't so straightforward due to the vertex and index format.
I have succeed to replace models in X360 stadium container file by converting .fbx to x360 format .pmem and .xatg Samples Content Exporter
https://github.com/walbourn/contentexporter and copying data from pmem file to rx2 with hex-editor, modifying vertex and index count in header files and assign vertex descriptor file in rx2 corresponding to xatg file.
Here is tutorial image for rx2 stadium models. Face index format is triangleStrip instead of triangles in other models so I'm not able to convert it:
https://imgur.com/EemOZ2C
By the way, here is updated rx2 Noesis script which support all rx2 models (stadium containers with textures and materials, faces, equipments, jerseys etc...). Use model script for models and texture script for textures and make sure there can only be one rx2 script in plugins/python folder.
Sorry, but I cannot help you with the rpsgl models yet.