Hello @hmbrattgmail-com,
First of all, thank you very much for using the plugin.
Regarding your query about the rental system, we do not have the option to allow travel agents to book narrowboats.
The plugin is not designed for the rental system. It is especially for booking the travel and tour packages by the user.
Now, as for the feature regarding the update of availability and pricing, we do have the feature of update the price and no pax of the trips but sending the updated availability via Google Sheet is not available.
As for the login, yes customers can log in to the site and make the payment. The customer can even book without logging in as well.
The plugin exactly does not address your request however the feature like login and update is available for the tour packages.
Hope this clears the confusion.
If you have any queries further then kindly let us know.
Thank you.