Hi Christi and All:
Cosmic samyama is a practice that is less likely to produce an overload by itself than to contribute to one if purification associated with ecstatic conductivity (kundalini) is accelerating, with self-pacing being ignored. Of course, the crown is central in this, as you point out, and your suggestions are well-informed by experience.
This varied effect, depending on the degree of energy awakening, is why the guidelines on when to undertake cosmic samyama are flexible, depending more on the individual than on a fixed order of learning. Cosmic samyama can, in fact, be taken on fairly early with little risk of mishap, after deep meditation and core samyama are in place and stable. It is an alternate learning track in the AYP system that is alluded to in the Eight Limbs of Yoga book.
Keep in mind that the marketplace is flooded with "guided yoga nidra" CDs and approaches, using attention points, that nearly anyone can indulge in with little risk of overdoing. That's because, for the most part, they do not optimize the samyama effect the way we do with cosmic samyama, and most people are not in a situation of rapid energetic awakening, yet.
AYP cosmic samyama is a different situation, especially when prudently integrated into a daily routine covering cultivation of
both inner silence and ecstatic conductivity, and self-paced accordingly. This is how it is presented in the Samyama book. Then this form of samyama becomes truly cosmic.
The guru is in you.