Helipads, such as those at Stratis Air Base, do not show up in the Editor, either with or without textures turned on. The only way to locate them is to scan the mouse over the area you suspect one is located and wait for the tooltip to pop up saying "Helipad". This makes accurately placing helicopters rather difficult. Please cause the built in helipads to show up in the editor.

Note, helipads placed manually by the user are not affected by this bug.