I would probably start by adding a button to the ribbon instead of modifying the Tridion Edit view with a checkbox.
It is also possible that in a future version of Tridion the HTML could change and your extension would need to be updated. I would suggest to compare the HTML from 2011 to 2013 for this view. I am guessing it is not changing too much. This would then give your extension a good 2-3 years, if not more, before there would be any risk of it needing to be updated.