One of the must-haves for your RV in my view is an inexpensive voltmeter such as this Camco 55263 or the Prime Products 12-4058 Digital Voltmeter. Even if you have a surge protector, not all of them can detect a brownout (low voltage condition). Anytime the incoming voltage is under 110VAC, you risk damage to sensitive electrical components, such as expensive air conditioners.
Having a meter such as these units will allow you to monitor your RV's incoming voltage and allow you to decide whether to disconnect or not.
Camco 55263 Analog AC Voltmeter:
One nice feature about this voltmeter is it's shape allows the use of the unused receptacle in the outlet. Unfortuneately, one feature not so nice is that the meter seems to be susceptable to static electricity, which can actually cause an error in the reading. Most voltmeters have anti-static coatings on the plastic bezel, but this one apparently does not. Perhaps it can be temporarly grounded to remove the "static cling". I have an anti-static brush used for cleaning camera digital sensors - perhaps I'll try to discharge the bezel with it.
When compared to a Fluke multi-meter, there is a 4V difference, which turns out to be about a 3.2% error, which is within the accuracy of many inexpensive analog meters. So if you want something a bit more accurate, you may wish to pass on this meter and buy a more expensive digital meter. However, I like analog meters in situations such as this as it can display any voltage anomalies "real time", whereas a digital meter cannot.
Prime Products 12-4058 Digital AC Voltmeter:
An upgrade from the Camco meter is the Prime Products 12-4058 Digital AC Voltmeter. This meter is inherently a bit more accurate, but it also features a wiring check. The meter can check for false wired circuits, but in all honesty, you should be using this meter to check out the shorepower pedestal prior to plugging your RV into it.
Running the same test on the Prime Products AC meter reveals that it is more accurate than the Camco meter.
Even with the slight error in the Camco meter, either meter would be satisfactory in your RV. The added benefit of checking the wiring for the digital meter is an asset, but only when checking shore power pedestals (afterall, you should already know your RV's wiring is OK).