Just to really throw the truck people in this thread for a loop...
You may not be able to do it with your F250, but you can do it with your
Prius! With the simple addition of a commercial-grade inverter connected directly to the hybrid battery pack, it is able to supply 5-6 KW (5 to 6 thousand watts,) for a long time. The battery discharges, the car runs the engine to recharge the battery, and repeats.
All this adds to the car is the inverter from an old server-grade UPS (the rack mount kind,) since they usually use the same voltage battery as the Prius' battery pack. And 5000 watts is more than my house draws normally. (Maybe if I had all my computers on, PLUS the electric dryer...)
Of course, as with any generator, you do need to prepare your HOUSE significantly for the addition. And the guy whose site is linked above took the extra step of adding a big bank of batteries in the house, and only plugs in the Prius when that battery pack is running low.
I haven't tried it on my Prius yet, I'm waiting for the warranty to expire. I don't want to break it in a way Toyota won't cover while Toyota is still willing to repair other problems, after all.
For truck guys, Chevy offers a 'mild hybrid' Silverado that includes a 2400 Watt 'generator' onboard. (It only gets 2 MPG more in the city than the non-hybrid model (about a 13% improvement,) and gets no improvement on the highway.) By comparison, Ford's 'full hybrid' Escape 36/31 only has a 1500 W 'car-style' inverter built-in, but gets 13 MPG better on the highway and 5 MPG better on the freeway than the 4 cylinder conventional model, and a whopping 16/7 improvement over the V6, while having slightly more power than the V6. (200 hp V6 vs. 227 hp for the hybrid's engine+electric motor combined.) Although since the Escape Hybrid is the same basic design as the Prius, one could probably make the same 'UPS' modification to it as to the Prius.