Question on Bewick's Wren nest and HOSP - Help!

I have a Bewick's wren who is just starting to build a nest in a hanging plant on my porch. Today a male HOSP came in and ran him out . Fortunately I was sitting right there, so and I promptly ran him off with a vengeance. The halo on the feeder is working well for me, so my question is can I do the same around the plant? Hang monofilament in a ring around it? Or do a Mylar spooker? The nest is not done yet, so I am afraid of spooking the wren in trying to spook the sparrow. Do I have to wait until the female actually lays the first egg to do a deterrent?

I also have a hanging nest box with a 1 1/8 entrance that I could hang beside the plant to see if he'll use that instead, and that should keep the HOSP out, but am unsure if that's too small an entrance for a Bewick's - I've seen conflicting info online.