Thats always been the way to start up ANY generator not just those used in RVs... The generator needs to be at full power and settled down before drawing power from them..
Your setup should have circuit breakers or transfer switches on the load side to switch in after the generator starts up... Plug-in generator before starting but have the LOADS switched out... Once it roars to life and settles down then switch in the loads.
I wouldn't like plugging into a hot source as well unless the device getting power is turned OFF.
Even when I just plug in drop cord for a lamp I always have the lamp turned off...
This is what the TRANSFER SWITCH mentioned above is doing... It doesn't switch to LOAD until it sees 120VAC for 30 seconds as described. This will prevent any arcing at the plug contacts if you plugged it in hot... If this was in my setup then I would start the generator with the cord plugged in first... Either way will not have any sparks in this case...
I think you can see where plugging in a trailer with all its loads turned ON will definitely draw some arcing from the plug when you plug-it in being hot with the loads engaged. That is inches away from your hands...
As the saying goes "Learn not to burn"
Roy Ken
