Hmm, it seems they only have the general CBSA number posted online (1-800-461-9999). My bad, for some reason, I thought they had a phone number in the Contact Us section
here but it's just the mailing address for each border crossing. I would just call the general CBSA number I mentioned earlier and ask them for the flagpoling hours for Peace Bridge or just ask them to redirect your call to the Peace Bridge office.
You're eligible to flagpole since you have a TRV and have a valid status (implied status). As for the documents you need to flagpole, just go through the previous posts in this thread. The only difference is that: in your case, since you're on implied status, you would need documents to prove that you're on implied status.
This link mentions that you would need: (a) Acknowledgement of Receipt of your PGWP application (b) Receipt of payment. Other than that, the PGWP documents requirement is the exact same for all of us.