Isn't that basically the same as them using a placebo? If just care has the same effect, then surely heavily monitoring them while providing a placebo drug should work.
But that doesn't test if the LSD helps in a non-clinical setting, only that the monitoring and attention helps
The problem is you can very obviously tell that you have a placebo because nothing is happening. Some studies mitigate that issue by giving a microdose but then maybe only the microsose is necessary? It seems like a hard problem