I'm trying to imagine how the logistics of that would work. First of all, how would you get the 50 foot battering ram inside the door? Let's assume that the walls are not breakable. In that case, you couldn't possibly manuever such a huge battering ram into that corridor. And that's not even getting into how people would be able to hold up the weight while walking through the first 2 phases.
On the other hand if the walls *were* breakable, this is possible. But in that case, there are actually easier ways to cheat.
If I were Lehm, I'd be too afraid to try breaking the walls because it might damage the whole thing to where the secret becomes permanently inaccessible. Or maybe the qualia would just teleport it somewhere else and he'd have to go searching the world for it. The current situation is pretty good, having it accessible all the time for thorough study, with nobody bothering them.
As for the battering ram idea, why not just tie the person to a cart and roll them through phase 3? That should fit through the door, or at worst could be assembled inside. I suppose it would be risky since you could end up trapped in there, so don't tie them so tight that they can't wriggle free in time, and put a timed release mechanism for added safety. But there could also be issues with the floor not being good to roll on the whole way. Large diameter wheels and rocket propulsion might help
But there could also be bottomless pits to avoid, or walls to climb, or corners to turn...
For the conga line, I'd think the biggest issue would be preventing everyone from running sideways. I suppose it depends on the geometry of the whole thing. Is it a narrow corridor, or an infinitely wide open space, or just a fairly large room that could be filled given a large enough number of people who can pass phase 2? Regardless, it seems impractical to find enough people.
And on the lucid dream approach, it can't be replacing your reality entirely because it's basing the constructed reality upon your memories of loved ones. So there's still more study to be done, analyzing its algorithm for how it chooses which memories to use. Perhaps it would be possible to plant "trick memories" that it will attempt to use against you but will actually cause you to walk forward. Though it's probably smart enough to see that and try something else if you don't go the way it wants you to.
Oh, and how about having Corona and Maytag tie Melter up and haul him through phase 1 and 2, and then release him to attempt phase 3 without emotions?
And have they tested the effects of a blindfold and earplugs on the illusions?
Certainly is a fun challenge to ponder on
I can't wait to see what the real solution turns out to be... if there is one.