Place water, sugar, and corn syrup (or honey) in a medium saucepan. Stir to combine
Insert a candy thermometer into the pot and heat over medium-high. Do not stir from this point on as crystals will form.
Place egg whites and cream of tartar in the bowl of a stand mixer.
When the sugar syrup reaches about 225°F, start whipping the egg whites to soft peaks. Approx 3-4mins.
When the whites are ready, the sugar syrup should be at 240°F. Remove from the heat, turn mixer to medium and very slowly and carefully pour the sugar syrup into the whites in a thin, steady stream. Don't let syrup exceed 240F or it may become grainy.
Once all of the syrup is in, set mixer to medium/high and continue whipping. The whites will deflate at first, but they will thicken and fluff up.
Continue to whip for 7-8 minutes, or until the mixture is thick and glossy.
Add in vanilla and whip until the fluff has cooled.
In a saucepan over medium heat, stir the white sugar and water until the sugar has dissolved and the mixture is boiling. Remove from heat, and let cool completely
Pour the syrup into a large mixing bowl, and beat in vegetable oil, shortening, and clear vanilla extract with an electric mixer on high speed to blend.
Beat in the confectioners' sugar, 1 cup at a time, until the filling is thick and fluffy. If it's too thick, beat in a tablespoon of water at a time until it's the correct consistency.