In the process it has been suggested to me by several homeless that I should spend at least one night out in the open to see what it's like to sleep without formal shelter or security.
This is a clear invitation to share an experience in order to understand it.
I would submit that you have an opportunity to get that experience in a small way not by making it cushier, but by making it SHORTER. Pick a spot that feels like a challenge and sit there for a pre-dtermined period of time. Welcome the various feelings that come, and journal them. That journal will stand you in good stead in your future conversations with homeless people and with people who are in a position to help.
The first thing their suggestion tells you is that you will probably not sleep "the first night," but that in succeeding nights you would find that you actually can, do, and MUST sleep. Part of their idea is that you see that it can be done, but what mental gyrations and exhaustion must come first.
If the idea of being alone for an hour or three makes you nervous, take along a journalist. That person can make some "security" arrangements to watch you both without YOU knowing it, so you will BE safe whole not FEELING safe.
Be creative. That is the heart of living in poverty-- resourcefulness.
And your own security-- a well-charged cell phone held in your lap, ready to use, in an area you know has good cell service.