What do you mean "UPS of sorts"? Are you going to build control hardware to handle the proper charging and discharging of the "super cap"? Or are you going to try and make a drop-in replacement for a battery?
In order to handle higher voltages, you will need to put the capacitors in series. However remember that capacitors in series reduces the overall capacitance. C = 1 / ((1/C1)+(1/Cn)). So if you put 4 of these in series they will handle 10.8V but your total capacitance drops to 100F.
Also, take note of what the ESR of each of the capacitors are. Since they are in series, these will add up. Calculate how much power they will be dissipating during charging and discharging by using the total ESR and the amount of current you plan to draw. Make sure if you cause their temperature to rise that their capacitance (or voltage rating) doesn't de-rate.
Lastly, pay special attention to the datasheet. Some capacitor technologies require de-rating, especially if the ambient + core temperature goes much above room temperature.