How likely am I to need 30amp and/or water extensions?

I need 30A, but I carry 30-50 and 30-20 adapters with me, along with a 30A extension cord. Also an extra white water hose and an extra slinky. Sometimes, the 30A receptacle is damaged or, in a couple of CGs in Canada, non-existent. It's OK to have a surplus, but if you're short by a foot you might as well be a mile away.