There are always alternate solutions to everything, most of all with websites.
In my case I use the same catalog index as my site intro page, due to my products that are always in the same categories and all.
In your case, since you have updates on normal base, why not try to alter the .htaccess file in your site root.
Something like this:
DirectoryIndex /catalog/index.html
I havent tried it myself, but it seams logical to work, that way everytime you have updated your HTML catalog, it will always be fresh. Or if you prefer not to use the HTML version do the same to your php version as:
DirectoryIndex /customer/home.php
I guess that wont hurt Search Engines, since they are not redirected by another page that lowers rating, they are just told on before hand where you are.
