Splash Page Organization

Hello,

I’m creating a website for a client, and she wants a splash page. And I know that splash pages are generally a bad idea, but it’s what she really wants.

Anyway, what I’d like to know is the best way to organize the files within the directory. I’m going to design the whole site, except for the splash page, in WordPress. And that means that the home page will be index.php.

Now, what I’m confused about is how assign a different page (splash.html) to be the page you see when you visit the bare address of the site. Because what I would like is to have the visitor enter the web address (www.website.com) and land on the splash page. And when they click on the image to enter the site, they are taken to the home page of the WordPress site.

And, ideally, I’d like to avoid using sub-directories if possible. I’d rather have the site go to https://www.website.com/index.php than https://www.website.com/wordpress/index.php.

Thanks for any help.