Rails make public,tmp and log folders outside the Root Folder

Everytime that the carrierwave save a file, go to app/public folder, and the tmp and log folder get bigger overtime, so, is possible to make these folder outside the RailsApp?

change the Rails.root.join("") on the application.rb is the only way to do it?

on mina deploy is possible to create shared_path if created ouside have to symlink the path?