Super easy!

Here are some facts that will help you:

You don't need to check Pirate's Cove directly to deal with Foxy. It's been dissected in his AI behavior that checking the camera in general will slow Foxy down, regardless of which camera you're on.

Freddy can be stopped at camera 4B, just outside the right door. This means that as long as you have your camera on 4B, he will never enter your office. You don't even need to be on the cameras, as long as the last place you put your camera was 4B, he will never enter your office!

Chica only comes from the right hallway. You probably knew this, but here's why it's important! You already have your camera on 4B, so this means you never have to check the lights on the right door unless you see Chica on your camera, which will save you some energy. You can still do this if you want, and in the video I'll link below, he checks the right door, but you don't have to!

The cameras only show one character at a time. In camera 4B, both Chica and Freddy can be there at the same time. The game doesn't allow both characters to be on screen at the same time, but they're still technically there. So if you check camera 4B and only see Chica but no Freddy, don't worry. Freddy is still there!

With that in mind, here's how to win every time!

Go straight to camera 4B and let Freddy get there

Check the lights on the left door (Close the door if you need to and checking the lights on the right door is not necessary, as long as Chica isn't in camera 4B)

Check the camera

Repeat steps 2 and 3

If you're worried about Foxy (which, if you're doing everything right, you shouldn't be), close the right door, check Pirate's Cove, and go straight back to camera 4B!

That's it!

I hope this guide was helpful.