An AskMetaFilter thread shares advice on campsite coitus. A good summary:

Actually, you can spend a very comfortable and sexy weekend in a tent, especially if you’ve got a little camping experience. Depending on how hardcore you are about pack weight, though, you’ll probably miss out on some of the nicer luxuries (a queen-sized air mattress, f’rinstance).

You might want to look into a two-person sleeping bag though. Seriously, sleeping in separate bags is like sleeping in separate beds, and it’s your honeymoon for chrissakes. At least make sure your separate bags have compatible zippers and can be joined together. (Actually, this is better for warmth too, not just for your sex life. Why waste all that body heat?)

As for the sex itself… well, so long as you’re in a tent, it’s not much different from sex in a thin-walled apartment. No operatic moaning or banging around unless you’re in a secluded site, but a little whispering and rustling late at night shouldn’t offend anyone.

The most common mistake is leaving a flashlight or lantern on in the tent. Please, please do not provide your neighbors with an X-rated shadow puppet show.

And there’s the ever-important bug repellant tips (No. 1: keep DEET away from your naughty bits).

Here’s a previous Two-Heel Drive post on the subject (not that we have sex on the brain or anything).