You're thinking about this the wrong way:
You are correct in stating that RAID0 with two SSDs is a bad idea. Lose one, and you lose the lot. But what you're suggesting, using two SSDs in two seperate places, well, that's just as dangerous: If you lose the
/www drive, your website will become useless. If you lose your
/mysql drive, your website will become useless. The end result is the same.
Additionally, unless you're serving millions of tiny files at gigabit bandwidths, hosting your static HTML files on an SSD will give you no speed boost, as there's almost no latency or disk access issues in picking up static files, unless you're doing it at a Facebook scale.
My suggestion: Take your two SSDs and put them in a RAID-1. It's still going to be fast (SSDs are fast by nature), probably faster than you'll ever need. There's not really that many servers that need an array of SSDs, not unless you're doing analytics on massive amounts of data, or have 100 servers all doing on-the-fly video encoding.
If you're still having speed problems after running things off a RAID1 pair of SSDs, start looking at your code and your database structures.