The inverter is only as good as the power source feeding it.
I use one on a regular basis for running a Peavy Amp and a set of speakers. It holds up fairly well. It's a 750 Watt unit.
BUT...plug in a few strings of lights AND the above load...the battery of the truck AND the alternator (I believe it's about a 110 Amp) have a hard time keeping a constant E & I coming...so I, sometimes, will watch the power inverter just cycle on/off.
kerry and BobK have the better idea...invest in a small, portable generator that will do/handle whatever you need. It IS the power source and you won't need to run your vehicle out of gas/diesel.
Your best bet before investing in any inverter? See if a friend will let you try one out (the size you're interested in) to see if it holds up to what you expect it to do. You'll find out really quick if it's what it's advertised. And, if you're looking at a quality unit, expect to pay anywhere from 11-20 cents/watt. But, keep in mind the ratings. Most (that I've seen and worked with) are rated at PEAK wattage, not constant/duty load. Make sure you over-size. Nothing worse than taking it out of the package, plugging/clipping it in and finding out your cigarette-lighter, in the dashboard, is higher-rated.
(Don't ask. Been there, been burned.)
Besides, you can use the generator anywhere you can't park/take the vehicle. The generator might be the smarter buy. But...watch out there for the pricing/wattage ratios...HONDA Gensets seem to be the GOLD STANDARD (As in "How much gold do you have?") and everyone else seems to come in a bit lower, with comparable options. Noise seems to be the #1 consideration for everyone and that's the "option" you seem to pay a premium for.
GL!