It seems there has never been a proper arrow weight mod even for Oldrim, but I'm wondering if it would be possible now that the official Survival mod does it. I don't really want to play Survival mode, but would love to have my arrows count towards my carry load. I guess it depends if the Skyrim internals were changed to allow for arrow weight or if the Survival mod does some crazy tricks. A simple mod where each arrow weighs 0.1 would be just fine.