Not enough information to respond about the 8k being sufficient, but I have tried running a 16k unit on a Xantrex 3012 inverter with 720 amp/hr battery bank.  It ran, but the amperage draw is so high it is not worth it.  Battery capacity is measured at a 20 hour discharge rate, or roughly 36 amps for that size bank.  The 16k unit draws something like 150 amps (12 volts), at which rate the battery capacity is much less.  You might get 30-60  minutes out of a large battery bank before reaching the 50% discharge point, followed by literally hours of charging.  Then there is the heat created in the batteries and inverter.  I tried it once and gave up on the idea.