The best option would be to shorten the time a “stride” needs, so your character walks out of the screen, or use a longer stride. With this super long take (600 frames!), each step will need perhaps only a tiny adjustment to extend the whole walk distance.
I have no idea what a 1/2 inch looks on your screen in ratio to your whole screen. How large is the screen? I also have no idea what happens in your scene, so I can only answer with the two tips above, or perhaps with a mixture of the two, shorter stride time, longer stride distance.
Typically in an extended scene like that, one would undoubtedly move the camera, perhaps that might support your move-out-of-frame target, to adjust the camera accordingly. Just a thought.
I hope that helps. Let me know if there are more details to consider so I can take a look at them. I’m happy to do so.
Enjoy your weekend.