I have a 30A system in my POPUP trailer and I bring along an extra 20A Extension cord so I can plug my roof A/C into it and not bother the 30A setup... In the winter months the oil filled portable heater is plugged into the 20A Extension cord circuit... Works good for me
Keeps me from messing with wiring changes inside the POPUP...
I have however run into a couple of campgrounds that frowns on you plugging to more than one provided electric service for what ever reasons haha...
I also carry a 50A to 30A long dogbone type adapter cord to do the opposite of what you are thinking sometimes. Most of us do the 30A plug-in and a lot of those campground 30A connections really look well worn... Plug into the 50A side usually looks great to use haha... Even tho I am plugged into their 50A side I still can only draw 30A where my trailer 30A breaker will trip off if I draw more current...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS