Motors don't really have a voltage limit (until you get to hundreds of volts when the insulation breaks down). What you see in the advert is just a suggestion for where it is likely to work best. You can run them at very low voltage (but they won't make much power) or at very high voltage (with a very small prop, to prevent it making so much power that it overheats). Somewhere in the middle is a voltage where the appropriate prop size is useful to most people, and that's what you see in the advert.
The amount of power the motor makes is dependant on both the voltage and the prop size. So you if you change one, the other should change too. Otherwise the motor will be overloaded, or underloaded (i.e. not making enough power).
Using a higher cell count battery doesn't necessarily add any weight. You just use smaller cells. For example, a 4s 1000mAh battery weighs the same (and contains the same amount of energy) as a 2s 2000mAh battery. If you run the first one at half power, the motor would turn at the same speed and run for the same length of time as the 2s battery. The only problem is that you have to decide whether to use a big heavy motor that can handle the full power, or a lighter one that works for the amount you expect to use most of the time.
I'll add that 16x5 prop is far to big for a 1600Kv motor, even at 2s. eCalc suggests that it would be making 450W at 70amps, while your motor can probably only handle 50W and about 7amps. If you want to use anything other than the recommended battery and prop, you should get an RC wattmeter to check that you're not overloading anything.
Finding the optimum power system is quite tricky. Generally a big slow prop is more efficient, but it reduces your top speed. So you need to know your target cruise speed. Calculators like eCalc will get you close (if you know your wing area and weight) but it's worth experimenting. You should also consider that most common designs have been optimised over decades of use, and while there's some scope for customising them, big changes will probably make it worse.