I think most campgrounds that offer 50 amp service, will also have a 30 amp service in the same box. If not, you can get a 50 amp to 30 amp adapter at many camping supply stores, or check with your local RV dealer.
I also carry a 20 amp to 30 amp adapter....just in case, as well as a 30 amp to 20 amp adpater so I can check polarity with a 20 amp plug-in check lite. And wonder why I have so many parts ??
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263