Index.php and index.html problems

I’ve read all the posts related to having an index.php and index.html hang out together and I haven’t found the answer I need yet.

Here’s the situation. I have had a WordPress site in the Root Directory for about six years and I’m looking to add a new service, so I need to create a Splash Page that will allow me to link to two different sites. I can’t move my current site into it’s own directory or I will lose all the SEO and page links that I have built up over the years.

What’s the solution, since you can’t put an index.html into the WordPress root directory and then link to the index.php, which would seem like the easiest solution. A few people mentioned the .htaccess as an option in some of the forums I read, but I haven’t been able to make that solution work.

I’ve seen a number of other people who have had this issue as well.