I have been working today on Courtenay Airpark (CAH3) in straight FSX. Oddly enough, only the default FSX scenery includes the Airpark Lagoon which both FTX PNW and UTX Canada missed! Although to be fair the FSX default lagoon was actually a perennial lake and it was the wrong shape.
Working with the default scenery I was able to create a water polygon and add the lagoon properly (correcting the surrounding shoreline as well). The best part was that I was able to put in a shoreline vector that matched the rest of the shoreline exactly. Orbx must use a custom shoreline for FTX PNW because I could never get a vector to match it, so it looked real bad!