Got to carry the various adapters with you on the camping trips... Many of trips with my 30A shore power cable I find the pedestal has burn and melted parts on it so no way will I plug into that. I will use the 50A to 30A adapter and plug my popup into that... It is safe to do as it only taps into one side of the hot wires... I also carry a HD regular extension cord and like to also plug into the pedestal 20A service to run my space heater or things on the outside when needed...
I call these PLAN-B items...
What you saw at a camp store might be the way that person is storing them too... Just plug them all together to keep track of them...
I don't care much for the small plastic adapters you see a lot of - they would always get hot for me when being used. I like the dog bone long cord type of adapters...
I also always have a multimeter along on my my trips and like to walk around the 30A and 50A pedestals and make sure they have the correct AC Voltages where it should be...
A good place to look at these thing is NOSHOCKZONE on-line... Lots of good info there...
50A Side
30A Side
Be very careful wiring up your house for the 30A and 50A pedestal connections. They are slightly different than regular house wiring... A mistake here will get very expensive for you when you first plug in... Lots of blue smoke...
Even when you have a professional do it can be dangerous. They too should be mindful this is for an RV Circuit. The savings grace with using professional electricians is they have Insurance to cover the blue smoke mistakes. If you do it yourself guess who pays for all of that haha...
Just saying...
Roy Ken