Just to clarify, you have 2 batteries on board, a starting battery and a house battery and you would be attaching the inverter
to the house?
In a word I think would be happy with an inexpensive inverter from Home Depot or Lowe's for the uses you mentioned (charging). The Stanley model PC809 has 800 watts of power, 2 AC outlets plus a USB port.
The best inverters generate a sine wave electrical
pattern. Cheapo units make a square pattern that some appliances
and many computers
don't like and won't operate properly. In between there are "modified sine" or "synthetic sine" models that usually do the trick.
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