Looks great!
So far this is looking awesome! I think the idea you had is probably the best way to go. What do you use to clean up the foam edges, is it wall spackle or something else?
I think it looks pretty good, but i had to look at the file and cut the two pieces foam at an angle, theres a guide here on therpf that explains it better, but like i said, your stuff looks pretty good already.