This mod was made to fulfill a request back before any DLC was released and it likely no longer covers everything (base game only). It's not planned to be updated and can easily conflict with other mods. I would honestly suggest using a newer alternative. 

Made at the request for someone on the Nexus forum/chat. Changes all loose mod items (the ones that show up in the "mods" tab) to weigh nothing. I know there are already mods that do this, but when you actually try to SEARCH for "weightless mod" none of them pop up. So here is one to help people trying to search!
For some reason, any mod created before adding this to your game will still have a weight value. I'm not sure why this is, this mod is very old now.