Create Chrome Extension - replace font on page with specific font -- 2

I would like a plugin for chrome built that will let me turn it on and off as needed and it will load a very specific font to replace the once on the current page. I have a font in mind for this with actually 4. the user controls will be on and off and which font of the 4 they want to use to replace the page with.

Here are the 4 fonts that need to work
https://github.com/christiannaths/redacted-font
So the user can basically load the webpage. Click our plug-in to choose the font to replace with. Then we defended the page. Once toggled on as I go to other pages it will automatically change them.

Next we have a need to make the text on the page disappear/invisible. But we need to retain the space that the text takes… so that it still holds its proper shape. So we are thinking we have two options. 1 try to inject styling to set font/text to transparent. 2 maybe try to replace all text with empty character https://www.editpad.org/tool/invisible-character

Seems both ideas might be good. But your plug-in should be in charge of getting our objective done in the most reliable way.

Please include timeline with your bid and the answer to 5-3=