Question, Chief...
In addition to the 50-ft 30A extension, is there also a shore tie cable from the RV to that extension? That is a LOT of wire, even when "correctly sized."
We camp at a lot of state parks. Many are 50A and of those, some have had their wiring recently replaced. It it's very hot (everybody running A/C), we get low voltage and breakers tripping. We like to position ourselves "just so" on the site, but lately I've decided we pretty much cannot get far enough from the power pedestal to need an extension. And our "30A RV Extensions" are only 25-ft.