I like your idea of trying to become better at sleeping. It appears as though we truly are quite bad at it -- we need darkness, silence, etc and still don't sleep well. However, I'm not sure if hormesis can really work for this. Hormesis is basically adaptation to moderate stress. I know from my personal experience that being stressed in any way is the worst way to try to sleep.
I have two alternative proposals for you. First, I know that I sleep best when I am either really tired or sleep deprived. However, that does not seem sustainable in the long term and definably also not something that traditional societies did. The other angle, which makes the most sense to me, is body state. I haven't really done much research in this area, so maybe someone else can add in specifics, but certain hormone imbalances of catacolamines, cortisol, seratonin, etc would certainly lead to trouble sleeping and getting those back in their proper amounts would solve any issues.
Another angle is light. I know that traditional societies often woke in the night and slept in the day, but possibly maintaining a natural rhythm of light and dark (not using many electric lights) can help the body "reset."
In regards to sleeping on less than comfortable surfaces, I have done that quite a few times in the past and it really just takes a little bit of adaptation. After a few nights you don't really notice any more.