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!