Are there any rules about circumventing "Gifts become tradable 30 days after purchase" ?

Ive never had a problem adding people then sending the gift. Just specify you will be doing so in the giveaway.

You can send them via mail without them being in your friend list(but they will be added automatically to your friend list when they accept the gift)

Sending a gift directly to someone in your friends list will also reveal your e-mail address.

That's how I send gifts; I prefer that over sending it off to a random e-mail address...

Never seen a single poll on this website with so unanimous results, not even a troll vote is present.

Are there any rules about circumventing "Gifts become tradable 30 days after purchase" ?

As far as Steamgifts goes: Yes.

Steamgifts uses the [bundled, unbundled, free] status of the game that was present at the time of giveaway creation.
So if you're patient enough, and find it desirable enough to wait out the 30 days, you can make the giveaway a few days after purchase, and set it to end after the end of the trade lock (and still get full CV credit for the game even if it gets bundled/free afterward).

Flip side, you could also swap out your Steam e-mail each time, but 1: That sounds like a major hassle given Steam's current security measures and 2: It actually doesn't always work correctly, occasionally still linking your previous e-mail. :X

In any case, I don't recall ever seeing any real issues pop up on the matter, so it may be an unnecessary measure. Likewise, you can certainly mitigate any risks by only offering your gift giveaways to groups you feel are trustworthy (or creating your own group with that in mind.)