That load center looks like it has the combined neutral/ground bar. You want separate bars. A main breaker is redundant - the shore power panel breaker (or unplugging) is your main disconnect.
Your inlet should be a male plug, not a female. With that inlet you'll have to make an extension cord with two male ends. If someone happens to plug into shore power first the male prongs on the bus end will be hot and easy to grab on to. I'd recommend a twist lock inlet that matches existing RV extension cords (like the Marinco).