[Tiara Open] What Size Portable Generator to run my A/C, microwave, lights off shore

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I have a 1993 2900 Open. It doesn't have a generator but has A/C, microwave, stove, etc. I want to run it electrical when anchored. I was looking at Costco's portable generator but what size would I need to run these items when not hooked up to shore power? Thanks!!