I have modeled pipe hangers and guides in AutoPIPE. (Not too sure if I am doing correctly). Ideally, a program would allow input of rod length because a hanger is not rigid. AutoPIPE does not allow this. Another program I have used, TriFlex, allows this input as an option.
When a restraint is inserted, V-stop or Guide, the user can input gap distances. When using a pipe clamp type hanger, I typically set the gap below and above the pipe to "0" for a V-stop. With roller type hanger, I use a gap below pipe of "0" and a gap above pipe of some absurdly high number, like 36 inches.
I use the same technique for guides.
Hope this helps!