You might want to take a look at J$J Hydrocolloid Adhesive Pads, labelled "Compeed" on the pad itself, but not the packaging. Currently, the packaging is labelled, "Tough Pads," but was "Advanced healing adhesive pads," until recently. Expensive.
Have used these instead of band-aids for all sorts of wounds, and found them superior in every way. They come around 2 by 3", but can be cut to the shape you want. After cleaning and disinfecting the wound, you just peel off the covering front and back, and stick the flexible plastic over the wound, wrapping where possible.
The older product info from J&J stated that moisture would evaporate through this product, but the more recent info does not. In any case, I've found that surrounding skin does not die and whiten as with other water resistant products.
It worked great during many hikes over where the Podiatrist recently removed a tonail, even though the Dr. was against any type of band-aid or tape cover. All covering is off now, so it is a moot question.