Hahahaha this is the most ridiculous thing I've heard this year so far. A projector and games consoles ****ing LOL
OK, I'll humour your ridiculous idea.
You'll need...
Deep cycle leisure battery or two.. (borrow from any caravan owner you know)
A pure sine wave inverter. (1000w should be more than enough) Approx £120 Ahh eBay to the rescue.. £100
http://www.ebay.co.uk/itm/2000W-100...-MOTORHOME-12V-DC-to-240V-AC-UK-/161064810221
A split charger. £44 off the bay
http://www.ebay.co.uk/itm/12V-6mtr-...d=100005&prg=1048&rk=2&rkt=5&sd=251439571836&
The car charges the deep cycle batteries via the split charger on the way there.
That should leave you enough reserve power in the leisure batteries to game, party, charge and light your tent for the weekend in SILENCE via the pure sine wave inverter, without your car battery going flat
DO NOT buy any sort of diesel/petrol powered generator.
You will have it thrown in the ditch in the middle of the night or they'll put a hole in your fuel tank... seen it happen.
No one wants to hear one of those things thudding away all weekend!, especially at night.