Maybe you're just not looking hard enough:
Our MEGA 1/2" shank router bits are your best choice when working with patterns that mount on top of the finished product. The solid carbide construction provides a long-lasting sharp cut, while the compression design of the flutes guarantees a clean cut. We don't cut corners, so unlike inferior...
infinitytools.com
52mm cutting length, 95mm overall length.
But for the 70mm deep mortise use case I'd just pull out my DF700. IMO, the right tool for that job.