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You'll want to use Vary HTTP header in your pages to tell google that you have different code for different user-agents: HTTP/1.1 200 OK Content-Type: text/html Vary: User-Agent Content-Length: 5710 (... rest of HTTP response headers...) Be sure you understand the pitfalls of user-agent detection as explained by Gogole here: https://developers.google.com/webmasters/smartphone-sites/redirects

Before I say that you are correct in your guess, let me preface by saying its probably a bad idea. You are correct in your guess From everything I've read Googlebot doesn't count iframe content as part of the page its looking at. However, if your site is bogged down by the amount of ads, chances are you're overloading your pages and getting docked by the post-panda google algorithm. Sites with lots of ads have seen decreasing rankings. Also, putting content in an iframe could be seen as suspicious by Google, further devaluing your site in its eyes. This isn't to say you can't make this happen and still rank in Google, but re-thinking your ad and revenue strategy could be the best long-term bet.

Thank you for you responses and advice!

I don't think ti is bad but actually encouraged. Ever copy of your content should have the same canonical tag. Obviously that includes the original. As I understand it, this is something you should be doing.