I don't know many addons with such level of customization.
I added KarmaDecay and Google. The last one - under your instructions.
And I have one suggestion to you.
Each high-level entry in Main Context Menu is very expensive.
On other hand it is more comfortable then in submenu.
You allow to user to choose which entries will be high-level and which will be in submenu under "Reverse Image Search".
Is it possible to combine the first of high-level entries with reverse image search submenu?
I mean - clicking on it will open this high-level search, clicking on one of its submenu entries will open an appropriate search of submenu.
Or it is impossible?
But anyway - I'm shocked by level of customization and thank you very much!
P.S. I also found out that this addon can be used not only for image search.
I added SEO searches and geolocation and it works. But the site that I want to check should have an image (actually it reports geolocation of image host).
If the context menu entry will appear not only when image hovering, but also links and even unconditionally, I think, I'd be able to check all what I want.