Driving EL wire with Supertex HV850 family drivers
The area is not really what loads the driver- what matters is the total capacitance (and the voltage, and frequency). The wires have a spiral wire on the outside which doesn't have as much capacitance per unit area as a flat panel. 

The HV816 claims to be able to drive 150nF, which they say is about 42in^2 of EL backlight. 

From this link, they claim the capacitance of their EL wire is about 1nF/foot, so 20m should be about 66nF, in which case the Supertex HV816 should be able to handle the capacitive load, and if the voltage and frequency are right, it should be okay. Check the specs on the EL wire you are using (or measure it).