How to include text intended only for reviewers in main manuscript submission? When I submit papers using blind review, I sometimes need to include text to reviewers that is not intended for the actual publication.

For example, 


Sometimes I include a URL to the OSF that has all the materials and data for the project. However, because the paper is blind review, the url is not yet active. Instead I include a special blind review URL with comments along the lines of "while this paper is under peer review, an version of the repository without author names can be accessed at ....". I often place this in a footnote.
Other times I might want to put a black mark through something identifying like the institution that approved the ethics of the study, because this might give away my identity. And I might want to include some text to the reviewers explaining why this was blacked out.


However, I often find that these kind of notes to reviewers end up in the proofs. Of course, at that stage, I can just ask the the people doing the proofs to remove this. But I think it would be better if I didn't have to do that, and I didn't have to worry about whether they would make the change correctly.

So, the question:

How do you include text in a journal submission manuscript that you want the reviewers to read, but that you don't want to appear in the main publication?

I've tried using footnotes and that didn't work. I thought maybe putting such text in a textbox with some special words might help.
Has anyone solved this problem?
You mentioned the online e-companion approach which works well in some situations. 

Another I've used is adding an Appendix to the paper so it is organically included in the initial submission only. We explicitly label it for the reviewers' convenience only and that it will be removed from the final version. After the first round of reviews, we typically remove it and place as an appendix in our Response to Reviewers. This has been convenient for us as authors and for the editor. It may not work for all situations.