So, this post prompted me to call RPR club lounge directly to ask about being able to use the lounge both prior to getting our room on check in day and after official checkout time. The person I spoke with assured me that we would have access to the lounge and any amenities from the time we check in (even if it's 7am) until we leave the premises on day of check out. I explained that we have a late flight and would likely stop by the lounge around 5p to grab a quick bite before heading to the airport. She said that would be completely fine.
Just wanted to share my conversation. Honestly, if we weren't allowed to use it before/after check out/in, I probably wouldn't do it. The ability to grab a few breakfasts, snacks, maybe light dinner are what make it worth the extra money to me.