Let me start with:
second-price auction
The auction type doesn't change anything, it will make no difference at all as to how much you get paid for your ads. The difference is on the advertiser's end and is only related to what price they bid in the auction and should not have effect on the final prices of the auction. The only impact, if any will be felt for a short period after the auction type is changed while bidders adjust their systems and metrics for setting bids.
In most cases most advertisers are not bidding specifically for their ads to appear on your website. The website is just one of many factors that advertisers can you for selection, and most don't care about the website, they care only about the user. If an advertiser is targeting "low RPM" locations, then there is not much you can do about that.
You can block those locations, but to what end. It is like someone offering to give you 1$ but you say no I only accept a gift of 10$.
The bottom line is that the more bidders are willing to bid on your impressions to better it is for you. Impressions are awarded to highest bidder, there is no scenario that exists where having fewer bidders produces a higher price.
Moreover any additional page view generates more revenue whether the page view is in "low rpm" location or not. Unless, there exists some reason that you have reached a maximum of pages that can be served and serving a page in "low rpm" location is preventing you from serving a one in a "high rpm" location. That then becomes a technical / server issue not having anything to do with Adsense.
If you want to make more money with Adsense there are only two things you can do.
1- Increase demand, by convincing advertisers that they should target your website specifically.
2- Increase supply, by convincing Google (other search engines too) that they should show more users your website in the search results, or convince your users to spend more time viewing more pages on your website.
Simple! Unfortunately both those points are difficult to achieve.