InDesign: Text-heavy pdf for mobile

in5 is absolutely brilliant, but it's not truly responsive, either and you're going to need a website to host the content. 

This feature seems to require that people read pdfs on their mobile devices using Acrobat Reader. How many does that? 

Once exported from InDesign to pdf, I publish my publications as flipbooks on Issuu, and I guess users just view it in their browser. So I was thinking more of an easy conversion of my file within the InDesign environment that allows me to have two design variations of the same document and let users decide for themselves which version to open, depending on their device.