I make my own gravlax - we LOVE it. I generally use 1/2 whole unrefined can sugar and 1/2 salt, cracked pepper and dill. I'm really not sure the sugar is necessary and I plan to make my next batch with salt only. It might be *TOO* salty, though. I also don't wrap it directly in plastic. Instead, I wrap it in a cheesecloth and then put the package in a ziploc bag, but the salmon is never touching the plastic. I'm told you can wrap it in foil, but haven't tried it.
I've made <a href="http://www.foodnetwork.com/recipes/ina-garten/gravlax-with-mustard-sauce-recipe/index.html" target="_blank">Ina Garten's recipe</a> several times and find it amazing. She only calls for 1/4 c sugar for 3 lbs of salmon... I'm okay with that amount and I've never tried reducing/omitting/substituting. Maybe maple syrup would work? She doesn't call for plastic, but she does have you cover the pan in foil and weight it, so you would have Al foil touching your fish.
If you don't use any sugar, the saltiness is really harsh. You can try it, and you might be able to stomach it, but I couldn't.<br><br>
And you do need to wrap it in something, but there's no reason you couldn't use wax paper or parchment instead of plastic. If you don't wrap it the edges will dry out and go kind of nasty, and also it will make your fridge a bit smelly.