I have trouble sleeping too. But sleeping is an interesting phenomenon. It's as much mental as physical. Now if your problem is really just physical (i.e. you go to sleep but then you wake up when your hip gets sore) then perhaps all you need is a better pad.

But if you can't GET to sleep then I think it's more likely mental. We don't realize how our brains take little cues from their surroundings to know that it's time to sleep. For instance you can buy a new, more comfortable mattress for your bed at home but the first night you might not be able to sleep because you brain was used to the old, uncomfortable one. But your brain learns quickly. So the solution might just be to keep at it until it becomes something your brain gets used to.

Noise is another thing that can keep us up in the woods. Especially this time of year it's amazingly loud out there (stupid bugs!). Earplugs can help.