If you don't/can't/won't carry it you should sell it on Craigslist. THe 50 amp extension will do you no good in storage. The only way you will ever be able to use it is to have it with you
I have a 50 amp cord that I just used last week at a FHU CG in Lancaster.
Nothing special or really weird about the site but my 50 amp cord would not reach without the extension.
I carry the ext cord at all times and truth is I seldom use it. However just like insurance is there when I need it.
If you are so close to your ratings that you can't carry an extension cord you are essentially overloaded already. You really need to consider an upgraded tow vehicle. I imagine you already know that.
In the meantime there is no point to pulling into a site and wish your expensive 50 amp cord were with you and not at home!