Really dumb extension cord Q

I think This part or your question is confusing ( If I am to use an appropriate size 15/20 amp extension cord (10 gauge) for shore power )? A 15/20 amp cord is not 10 gauge, a 10 gauge cord is usually 30 amp unless it has 15 amp ends on it. If it does, take the ends off and put regular rv plug ends on it and it will be a 30 amp cord. Then if you plug into a 30 amp rv type plug, you will have 30 amp service. Like others said, the lowest amp device is what it's de-rated to.