*"For instance, it better send "expected" headers (User Agent, Accepts, etc.), a...

"For instance, it better send "expected" headers (User Agent, Accepts, etc.), and it better have cookies enabled..."

How are these challenges exactly? Just set the user-agent and enable cookies. Done.

"...also operate from many distinct and perpetually changing IP addresses."

Okay. Change the IP it operates on every few days.