Your suggestion looks reasonable to me, although you didn't mention how to get back
For that I would suggest the automatic on-the-fly creation of the back link (pushing on a stack of back links?), then using the back button to return. (I don't like the amount of work involved in embedding the back links in the footnote text.)
There was a discussion of footnote implementation in the Workshop/Epub forum some time ago; it's probably worth reviewing (left as an exercise for the interested reader
).