Put the resistor in, you either dissipate power in the resistor, or do it in the tube itself. Better to run the tube within ratings, that run it at around 4 times the voltage, where it is extremely likely to suffer from arcing over between the anode and the other electrodes, as they have been built to withstand 50V only, likely fine to 100V, but above that arcing, or just simple slow build up of ion deposits, is very likely. Resistor and a zener diode to clamp to 47V will work. Heater run at the specified, if you want longer life put a series resistor to drop the voltage to the lower end of the allowed filament voltage range, and thus also have a bonus of inrush limiting when cold. Running at lower heater current, and thus making the heater current limited, will strip it badly within a short time, and kill the tube. You want full emission with a VFD, it will otherwise band, as the limited current is going to flow to the closest portions o the anode.