Extend SU 3D lines like they were 2D

I need to perform this extesion line but it’s not possible.

In sketchup you’d hit the first point, and move the second point on edge, hold shift and start infer the end point.

In layout it’s a lot more intricate and envolves holding down shift while scaling the line, so you have to use 2 commands and can’t infer.

If the model view would be an actual 2D the issue wouldn’t arise. But the only way to acomplish that is by exploding it wich defeats Layout’s purpose of syncing with SU.