New stage config option - 'remote trigger only'

I have a build plan with a number of stages. The initial stages run automatically and the final job triggers events outside of bamboo before completing. This stage goes green at this point as it does not wait for a response but the process that has been initiated elsewhere is still running.
The external process completes later and it then calls the bamboo api to initiate the next stage in order to complete the remaining stages of the pipeline.

So currently, we have to set the later stage as a 'Manual' stage to achieve this. However, this means that a logged in user can click the stage run button and start the second set of stages before it is ready to proceed.

I would like an option to have a manual type stage that can be triggered through the API, but does not display a run button on the web interface.
I would call this a 'Remote Triggered' stage and be a check box on the stage config like the 'Manual' option.