Can I Have My Cake And Eat It, Too? (CNAME Problem)

I have a bit of a conundrum on my hands...

I purchased a subscription to Elegant Themes, just because I like what they have to offer and also because I fell in to all the Divi 2.0 hype.

Anyways, my squeeze page is hosted on Instapage, and I have a CNAME redirect (main.mysite.com) to pageserver.instapage.com. My "Thank You" page is also a CNAME redirect from thankyou.mysite.com directed to pageserver.instapage.com.

My top domain, mysite.com, uses a 301 redirect to main.mysite.com, and that's where my conundrum lies - I want to be able to use one of the Elegant Themes Wordpress themes as the main page of my website/blog. I want the subscribers to be able to use mysite.com as the main site, yet want to use a "forced" squeeze page, also. I can't use "www" as a CNAME, because my host says it's already in use, even though it doesn't show up in the CNAME list anywhere.

Is there any way I can have my cake and eat it, too?

Thanks,
Phil

EDIT: Okay, so I just looked at the Advanced DNS Zone Editor (as opposed to the Simple DNS Zone editor), and found the "WWW" CNAME there. I guess I can use the "WWW" and do a CNAME redirect from www.mysite.com to blog.mysite.com. Or should it be directed to mysite.com/blog? Does that sound correct - before I go and screw up the whole thing?

EDIT #2: Okay, so I had to install WP to mysite.com/blog. Made a subdomain (blog.mysite.com) so that the CNAME would be a "valid zone name" for the www subdomain. Redirected the "blog.mydomain.com" to "mydomain.com/blog" so I could then use the blog.mysight.com CNAME for www.mysite.com. www.mysite.com STILL redirects to mysite.com, which in turn redirects to my squeeze page.

Help!