Is it possible to build a fully Di2-equipped (i.e. front and rear derailleur) bike without buying any Shimano Di2 brake/shift levers? Specifically could I use a pair of Shimano SW-R600 remote climbing shifters as the basis for the system, plug them directly into the junction box, and go from there?

The ad I linked above specifically says that Di2 brifters must also be in the network for these to function, however some TRP hydraulic brake-only levers support attaching these switches to the lever bodies:

https://www.trpcycling.com/product/h...2-adapter-kit/

Since it would be very strange to run two sets of drop levers on one bike, this implies that it can be done. Does anyone here have experience with this configuration? The climbing switch I linked to mentions that it works for the rear derailleur. Is there a way to install two of them and have one shift the front der?