
Hey Ira, Thought you forgot us. Nice pic.
I think the border is great. If the scallops don't look right with the opening perhaps you can put the scalloped part into the opening and the rest as framing.
If your corners don't come out perfect use some wood fill for the gaps. If you use the good stuff it shouldn't show.
Glad you tried it anyway,
I personally would not miter a frame that was going to have a door. So I guess I agree with the others.
However, you requested info about mitering and my personal opine is that you practice. You might supprise yourself.
If you cut your pieces together or at least mark where on the molding you want to match at your corners, you should be ok.