So I'm half-expecting a "Duh, of course" answer to this, but you can use Widow's Watch to search for a Riders of the Red Fork whenever it activates, right?

I guess the more important question is what exactly counts as a "search effect" for the Riders? Anything with the word "search"?

And yes, I did check the FAQ

Shenanigans said:

And yes, I did check the FAQ

~Dude, that will not do. The only hope is ktom.

You can search for Riders, but there is a doubt if "top X of deck" is also a deck:Galbar Glover, searching

Only if the Riders were in the top X cards of the deck when the effect was triggered. Nate's explanation was that the Rider's effect modified the search criteria, not the search area.