Make your floor 8 feet then push it back 2 giving you a little porch.

You will never stop them by yourself. I'd still use the Amdro. It's a slow acting bait that will be fed to the queen s who will then stop producing new ants. Good luck.

You need to kill the ants first. I would either crawl under the house or trickle Amdro into that crack. Then you can glue a trim piece over it.