Six possible end details for a flat truss (Pratt 4 panels), there are probably others but these seem to be the most common:
1.) Mansard w/ Parapet
Both Mansard configurations can also have an optional overhang as shown. The Parapet configuration should allow for customizing the thickness of the parapet wall.
View model here:
This truss type with its many end configurations would work well with an HTML UI, that is the direction I will be going with future user inputs and interfaces since the ability to customize is unlimited.
With the flat trusses I will initially offer both Howe and Pratt with the ability to utilize a low slope or zero slope.