Based on your requrements you can use this module.
All your sales persons vists to client and project related vissts can be enterd here.
Access management: You can allow access of visits to selected users by allowing user and manager level access. Users will be able to see own visits only.
Users can enter related iformation by setting proper sale, project and task information. For more clerification we have added calendar and pivot views also.
Once you have vists in system you can invoice them to clients. Single invoice can be created per client or project using proper options in
Created invoice with proper details as shown in image. New option in Accessrigh management for giving access.
Other configurations in Odoo
No extra technical knowledge or configurations requireired. Just install the module and enjoy functionality.