Are you an administrator? If so look into the permissions section
for other users to just view without having R/W access.
The process you defined will work just fine. As you mentioned the viewers will have to have read access to each of the project folders. You will also need to setup workflow state permissions so that they only have read only permissions in the "released" workflow state only.
If you are an admin to your vault. You can set up a task to generate a PDF and\or DXF file when a SW dwg file passes a transition. You speficy where you want the output document (pdf and\or dxf file) to be saved. This save location can be directly under the vault , and only allow Release viewers acces to that folder or external from the vault.