Been homeless for years. The weather has it's seasons and anyone knows ahead of time generally what it's going to do, and "calculating survival" is a matter of "thinking ahead". Sexual assault runs rampant everywhere- college, work, military service, etc. A lot of times drugs and alcohol are involved and everyone would be a lot better off if they spent less time inebriated. I mostly prefer to avoid the homeless concentration camps for many of the reasons you mention, and a lot of the homeless feel the same way about it.
But let's say worst case scenario, you are up in fucking Alaska in the fucking cold and didn't bother to think ahead, and need to "calculate survival". Then you just ask anyone for help, the same thing anyone - homeless or not - should do in the same circumstances. Then, once the self-created disaster is over, go back to spending buckets of time in blissful contemplative introspection.
Was that really so hard? Because if someone asks me for help, I happily I do it if I can. Maybe that's where karma matters because whenever I really need something, and it doesn't happen all that much, I know that I exist by personal experience and I know from that that others like me exist as well. So others like me, who are also happy to be kind and generous to others, have this uncanny way of making themselves present in times of need. Stingy graspy people don't have that luxury because they don't see the world in the same way. So don't believe the hype, it pays to be good.
As far as actual food, the homeless are just as obese as the general population, there's no statistical difference there, and have you seen waste statistics? There's no shortage that people and businesses are otherwise going to be throwing away. It's the responsible thing for them to donate, along with their secondhand scraps of clothing. After that there's food that has already been thrown away, an endless goldmine for anyone who knows what they are doing. Then someone could always put in a little elbow grease, panhandle themselves up by their bootstraps, and ask anyone for something to eat. We are all one big family of humans and if someone just asks nicely, getting food is like the least burdensome of all things. I very rarely if ever ask for money, it's always 100x harder to get whatever it is that way.
Most of my days are like 8 hours of sleep, one or two hours of housework, where I fold up and stash my blankets, figure out where to get some food and wash up if I can. Then what? It's like 14 hours of doo dee doo etc etc. Sometimes I go hang out with the homeless ladies, they like the company and I'll dig scraps of bread out of the trash can so they can feed the birds. Everyone's happy, what's the big deal here?