More or less. It's more about load. You can have zero load at 3,000 rpm (sitting in the driveway) or be going up a mountain at 60 mph at 3,000 rpm. One is very light throttle, one is very heavy throttle.
I don't think you should try to use the Mirage to power your "RV" needs. Using the Mirage to power "self-contained short-term in-car camping" is what I was thinking. You could do that.
If you're creating an RV, buy a good inexpensive inverter/generator. They make them very small and very quiet these days. Not much louder than your car idling.
Look for one with a good brand name, good noise ratings, and good reviews.
We use a generator to power our equipment for autocrosses. (the timing equipment is battery powered, this just runs the laptop, a fan, a 32" tv monitor, and an LED timing display... probably 300-350 Watts) We don't put a lot of load on it, but the way we use it is less than ideal. Basically, it its in storage most of the time and gets used for about 8-10 hours every other week, and if we remember... we do some maintenance on it every year.
We've been through about 4 generators:
1 - 20+ year old generic 3,000 watt generator. Just a cheap $300 generator that you'll find pretty much anywhere. Old school. Big, loud, gas-sucking engine. The pros were that it was reliable and cheap. Rebuild the carb every few years and put a new spark plug in it every now and then, change the oil every year. It usually started easily, and worked. Cons were that it was LOUD and used about 4-5 gallons in our 10-hour day.
2 - Almost as old Yamaha generator. It was a little bigger, but a better brand. Somebody traded us for it because they wanted something smaller. It was equally reliable right up until it wasn't. Pretty much the same as the other one, only bigger and maybe a little quieter, but still loud. Slightly less thirsty, but still used at least 3 gallons in 10 hours. I opted to replace it before I fixed it. When I did fix it... it was an $8 capacitor that failed. Took 5 minutes to replace, and somebody is still using the thing for backup "storm power".
3 - Bought a small $150 inverter generator. (
This One) This thing was AWESOME! Used less than half the fuel. Much, much quieter. Started first-pull every time. And about 1/4 the size! Lower capacity output, but it met our needs. We loved it! Until the carb crapped out after about 2 years. We replaced the carb once for about $60. When it crapped out again... we thought seriously about just replacing it with another one just like it. We got a good 3-4 years out of a $150 generator! But, when it failed, it failed without warning, and that was annoying. After a carb cleaning, it's back in use also as backup "storm power".
4. - Bought a $700 Generac inverter generator. (
This one.) Specifically searched for reliable, quiet and efficient, but without being in the price range of a Honda. (if you have the money, buy a Honda) It's way larger capacity than we needed (2200W for our 350W load), but it's damn near silent when switched into "economy mode", and we get through 10 hours on about 3/4 gallon of fuel! It's been flawless for nearly 2 years so far. It is stunningly quiet. Would get a little louder under more load, of course.
So... yeah. Rather than buying a big inverter and torturing your car, just buy cheap generator. Even the super-cheap one would get you by for a while.