Hi Jon,
You can find examples of an Eclipse Launches inside this
GitHub repo
You can launch an Eclipse product also as an exported fat jar from bnd, but it depends on your use case.
You require the Eclipse Product only when branding and/or native launcher executables.
There are slides from my talk at the EclipseCon Europe -
Eclipse RCP with bndtools - available describing the RCP / bndtools workflow.
The example uses a ant/PDE build instead of your requested Tacho, but it works ;-)
Feel free to get directly in touch with me if you have more detailed questions. But I must admit that I cannot explain the Tycho way to build Eclipse products.
regards,
Peter