I will tell you an example unloaded. Lets say that you put a wattage device at 7,4 watts with a wire made at 7,4 ohms. The device will see the resistance and it will set the voltage at 7,4 volt so it will reach the 7,4 watts. That is 1 ampere of current to the wire. You think that you will produce any smoke like this?
Another different example. Lets say that you put the "right" resistance on this wattage device, that is 1,5 ohm and you set the device at 10 watts. But you put a very fat wire with a diameter at 0,5mm. Will you produce any smoke with a fat wire like this?
Almost the same applies to voltage devices. Those devices just increase the voltage. Increasing the voltage you send more current to the wire. But you dont know how much current you have to send to wire, you just try and check and try and check again until you will find the point you can vape. And you do this in every wire you make.
Those voltage devices have limits too. They cant feed with the nessesary current a wire at 0,5mm for example and they cant feed even a thin wire made at 7,4 ohms because they will set the voltage at 7,4 volts (not all devices can do that, most of them go up to 6 volts), so they will send only 1 ampere to the wire. But 1 ampere to a wire made at 7,4 ohms is nothing.
The conclusion is that I cant give you a solution to what you can vape until VIR comes to the market. When this happen then you know what my suggestion will be.