> What I would like instead is a "view source" item in the right-click menu, and no icon. (I have too many icons already!)

That is already possible - right-click on the CRX button and choose "Hide this button".

If you regret your action and want to show it again, go to about:addons, Extensions, and click on Preferences of the extension. Then tick the checkbox with the label "Show a page action button in the location bar of extension installation pages.".