.htaccess crap

[cd34]

You might be able to use something like

RewriteRule ^(.*)\.html$ $1.php [QSA]

but then you would want to also make sure the destination file exists, etc.

I'm not sure why your hosting company won't turn it on for you -- the load generated is exactly the same.

If you can't parse .html pages with php, and you rename all your pages to php so that they can be parsed, there is no difference in terms of cpu horsepower required to serve your site.

The right solution is to just have them turn on php parsing for html pages. I'm not sure what your hosting company's resistance is to doing that.