I use this brand:
http://www.weatherbeeta.com/
The cover I have for Jala (standard female) is 40cm or 16" (neck to tail measurement). This cover is really warm and waterproof.
Subaruthie, the hoodies you made look so cool! 
OK - I don't have a clue how to trim a tail. Do you think it's possible to get Daisy's tail in better shape? It has gotten very bushy in the last few weeks! The actual tail stem is very thin compared to the fur camoflauge.
Side View
Top View
Do we win the contest for bushiest tail?
that's not a tail…that's a brush! 
That is actually very cute!
My parents tri is incredibly naughty too. I remember her best stunt was standing in the middle of the dinner table helping herself to cake! One of the guests left a chair out.
We have a store here (won't mention the name) where some people let their dogs run around without a leash! It has never been a problem, but I do pick Jala up when there are little kids around. I just don't trust them. They usually try to touch or pull her tail!
I would give your dog the chance to have a behaviorist/trainer work with him for a couple of months.