I certainly agree. Peat not only would add to the weight but also increase the acidity. I purchase super coarse perlite by the 4 cf. bag. That's a lot of perlite. Because perlite is so light, even a huge bag like this ships for a moderate amount. You could also add something like cypress or another hardwood mulch. This adds organic matter which will break down over 1-2 years. Until it breaks down, the mulch will open the soil.
