A few thoughts here:
There is no 5-60 (or at least they are so rare that no normal person has ever seen one). I think you mean 6-50.
I definitely would not buy a second mobile charging cable.
Option 1: You probably don't need to buy anything or keep a cable in the car all the time. That is only to plug into outlets. Any kind of charging stations don't even use that. And it would be really odd to just magically find yourself teleported way out of town and not near any kind of charging without you having decided to go on a trip, where you would have decided to go ahead and take the cable with you on purpose for that trip.
Option 2: If you do need to buy an extra something, I agree with
@Sophias_dad that a wall connector as a supplemental thing to go with your mobile charging cable is a better choice.
As to are there 3rd party cables? Well, for the main charging cable, no, that's basically from Tesla. But if you are talking the little changeable adapter plugs for it, yes, there is a really good company called EVSEAdapters.com that makes adapter plugs for many different kinds of outlets that Tesla doesn't sell. So if there is some weird outlet type you would need to use, you could buy an adapter plug from them.