This the reason I was asking...
My Inverter/Charger is made by Magnum Energy Inc., and they say to, "Look for an inverter that has a surge rating 4x the continuous wattage of your microwave."
Mine is the model MS 2012 which is 2,000 Watts rated, with a surge of 3,300 Watts for 5 sec.
So, since I already have the MS-2012, I'm going to look for a microwave with a continuous wattage rating which is 25% of the Inverter's surge rating instead. If I take an average of all four surge ratings listed, I come up with 2850 Watts, which is right at the 5 minute rating. So, 25% of 2850 is 715.5 Watts. But, since the highest rating is 3300 Watts and 25% of that is 825 Watts, I'll look for a microwave in the 700 to 900 range and should be OK.