Let me start off by saying that this is a fantastic thing to have a discussion on, and I feel it my moral duty to confer my own way of dealing with bad/mad trips.
I won't list off my whole experience history, but I've taken most psychedelics numerous times, and DMT 3x now; at the time of this writing. The 3 times I took DMT were all orally, so it lasted 4+ hours.
You've done some others, so I won't waste time talking about a positive mindset, and you're right, that doesn't really apply to DMT.
The past 2 times, I've spoken with the Gate guardian (I'm assuming to be the Aya brew), and she's always given me guidance before the DMT universe hits real hard (the MHRB brew):
1. There are plenty of tricksters out there, so you need allies
2. Open your eyes to disrupt the nonsense if things get too rough; just long enough to break the spell
3. The gate is always open, and that works both ways...
So my ultimate advice when entering the DMT verse is to find your allies. Sometimes it's an errant thought, sometimes it's the questions you pose to the entities you meet, but every single time I've tripped on The Molecule, it has gone south at some point. That's where your allies come into play.
I can't describe the feeling of being overwhelmed and dominated by something, and then seeing my spirit friends pop out of nowhere, uncalled, and deflating the beast into something small and insignificant. My good friends that I would journey with through everything.
I've also noticed that examining things too intensely in Hyperspace will inevitably lead to a bad time. The little machine elves always appear, doing their work of creating the place, and they're just a bunch of rapscallions is what they are. Not evil, but they are very mischievous. Little tricksters that like it when things fall apart
I use music that resonates my current mood to calm my mind, take a walk outside without electronics and go through my intentions so that I know I'm sincere and not a bad mannered guest when I enter the magical world.
Tomtegubbe does have a point. The last trip I took, I met the King of Snakes, and I'll tell you that I think he's the most powerful entity I've met thus far. He didn't want anything from me or give anything to me. He just laid down the rules.
The King of Snakes had 13 cards, and the only time he had to play one was when one of my errant thoughts I had was of mocking my guide. It was defiling the sanctity of the DMT verse is what it was.
That card alerted every single entity in the DMT space that I was sacrilegious; I had no respect, and laughed at them. Needless to say I got on my knees and spent a good minute convincing them that I was not meaning that, it was just a stray though that became reality, but that was wildly terrifying.
Be respectful, and find some good friends (spiritually). My two closest spirit allies will see me through anything, and my true Guide would pull me out before I fell hand to Demons that would cloud the third eye. Why would infinity exist if you only experienced Hell after all? It must stretch through everything.