No, I think he means converter, not inverter.  Converters convert AC power
to DC power (for the lights and a few other things in an RV)

Check out:
http://www.rversonline.org/ArtTipsConverter.html

and

http://www.rvdoctor.com/rvdoctor303.html

I would think a converter should last for a long time.  It is pretty simple
circuitry.  The only moving part is the cooling fan.  If that dies, the unit
will cook.  Remember, the converter (and therefore the fan) is always
running if you are hooked up to AC power, even if you have nothing connected
or turned on.

Two things I would look for:
1.  Incorrect wiring or a short after the converter, putting a load on it
all the time.
2.  Fluctuating or spiking AC power coming in at the campground.

You can put a simple voltmeter on the incoming AC power (and there are
fancier testers available).  The voltmeter won't check for voltage spikes,
though, only that the voltage is about right and doesn't fluctuate a lot.

You can get an ammeter and put it in the input line to the converter.  Then
see how much AC amps it is drawing with nothing turned on.  Then unplug the
DC fuses one by one and see if there is a large drop,  If so, that circuit
is a peoblem.

HTH