Your mileage may vary, but I ran two separate Azure trial accounts like this, and a friend ran eight (160 cores!). Neither of us ran into any problems from Microsoft, even though we each used a single credit card for all our trials.
Wow, that's an idea I hadn't considered. I have that $h1tty paypal CC, I think I'll attempt it with that one.
Im guessing you're gonna need 8+ new emails to register right?