Heh. How about just put the labels on the sleeping bags? Seriously, if being totally unsupervised alone in the woods isn't already going to lead to temptation, then having the same piece of nylon over you rather than between you isn't going to change a whole lot.
How about this? If sleeping in the same tent is unwise, just don't take tents and sleep out in the open
If you grant the camping tent at all, then after that point any line drawing becomes very subjective. If one couple can safely camp together in separate tents, then another can safely do so in the same tent.
For many (most even?) it would be unwise or even very unwise. But what may be unwise for many does not create a sin for all.
Fallacy of slippery slope. Let me demonstrate...Take each of those questions and apply it to the issue of, let's say, engaged couples kissing. I can already promise you that any answers you give can be easily negated or pooh-poohed by those who believe that waiting till marriage to kiss is the only right decision for Christian couples. And lets not even mention the issue of alcohol.
The point is that even though I might provide an answer to every question, it would be pointless - those who absolutely feel its sin are going to deny that such answers are valid. Don't believe me? Then go ahead and answer the questions in light of kissing while engaged and watch as I demonstrate that any answer you give is insufficient. Do that and I will let you do the same for my answers.
Otherwise, rather than waste my time giving answers which won't change the debate and I am certain will instantly negated, let me just assert that some couples can do such to God's glory. Thats not to say that couples as a general rule should, or that there is no real danger in this trip, but that still is a far cry from it *necessarily* being sin. Limitations of your imagination and conscience do not create a *sin*.
It starts with temptation, yes. But an activity which might give an opportunity for temptation to lust is not a sin. Otherwise, men should gouge their eyes out lest they ever gaze upon a woman and thus create a situation where they are tempted to lust. Applying the slippery slope fallacy to this verse as you suggest would lead to all sorts of absurdities.