I'm sure this is the reason snow leopards carry the ends of their tails in theirs mouths

lol!

I'm getting a sense that it would probably be best to make tails, with zippers to let the owners access to removable innards, so one can easily launder and dry the fabric layer. And if the innards are up for it, you could toss it into a dryer for an hour to kill any potential pests.

Nope on both accounts. Firstly, the innnards of a tail have to be packed perfectly or else the tail can look deformed and weird, have spots that are too thick or too thin, and pulling them out repeatedly would mess with the look of it and be more trouble than it's worth. Secondly, the filling is typically polyfill, ie: plastic, and putting that in the dryer will lead to a pile of melted slag and possibly a dryer fire. Not the slightest bit worth it.