If you are building a Mazot Savoyard, I assume you will be going with the typical large roof overhang. If that is so, then this joint is fine to use. Brian's concern about water seeping into the joint is more important with american style cabins with minimal overhangs.
This building is closely related to the Swiss Alphütte or the Alpine Chalet of Romandie
To make such a template would not be so difficult, but you have to know a few things first:
What are the sizes of the logs being used? and Are they all the same? The size and location of the joint must change to match all three logs in a single connection point.