This is a quick study of a post frame roof using doubled trusses with 2x6 purlins @ 24" o/c. This is pretty typical for a pole barn or post frame building constructed locally:
View model here:
Notice how the rake and fascia boards are raised above the trusses so that they are flush with the roof plane and purlins. The overhang can be achieved a number of ways but one method is to extend rafters from an inboard purlin and also attach to the post as shown.
There are a number of other ways to frame the overhang, a quick search online will attest to this. Sometimes a header is used between posts which allows for a truss spacing which is closer than the post spacing.
Purlins position right at the peak seems fairly standard, based on some plansets that I have.
When you add end walls with posts you can usually eliminate the doubled truss at the gable ends and you often will see a gable end truss that has girts (horiz. members) instead of studs.
With a purlin roof I almost need to create a separate menu item and module to properly deal with it.
Here is an interesting double truss design but with scissor trusses:
