Unless you're crazy, stupid, or a member of the Ghost Squad, chances are you are going to want to try and stay warm for the upcoming Winter Tough Guy. Notoriously one of the coldest races out there, which in turn contributes to it's difficulty. (read more about Tough Guy here).
Unless this year is as mild as 2016 where even I ran in bare arms (did anyone else feel that ruined it slightly??), which is highly unlikely, you will need to be well prepared.
There are a few people who claim that true Tough Guy honour is only achieved by taking part in the race being half naked and making it as hard for yourself as you can... to me that's like saying you only took part in the World Champs properly if you didn't train and wore your road running trainers.
There is so much talk at the moment about what is best to wear, and one of the most important points I can make is that it's individual. You need to know your own body and how much you need, what I would wear would make another person hyperthermic, however, saying that, here is my experience, take from it what you will, and please get out, get wet and cold and test your kit before the big day.
Merino or not? Personally I say not. The only time I wore merino I got hypothermic. My reasoning is this: I like fast drying base layers, in my opinion, merino holds water but doesn't keep you warm and insulated like neoprene does. Forgo the merino and stick with a thin base layer. My favourite layers are from Aldi and are not available all year round. I have a pair of shorts which go under my shortie and a long sleev top which also goes under the shortie to prevent chafing. Any thin, synthentic fibre, tight layers will help.
As mentioned above I wear a thin base layer under the shorty (like you would wear a rash vest) but try not to have too much between the neprene and your skin. Any other layers I put on top of the shorty.
I don't know many people who have worn full wetsuits, but those who have do not recommend it, they claimed they got too hot and dehydrated.
I know many people who swear by neoprene socks. I don't. I find once my feet are restricted they get even colder. I would need trainers in a size up in order to wear them. Thin socks such as nike drifit and good fast draining trainers are my best option.
Although you may get hot wearing gloves for the run, they are invaluable for the killing fields, and can easily be tucked into your waistband when you don't need them. 3mm is ideal, any thicker and you lose dexterity.
Even if you can get away with running in neoprene gloves before you get wet, you probably will overheat in a hat, however, I can't recommend having one enough. Once you get to the that freezing cold water, before you've even had to go under you need to keep body as warm as possinle, and neoprene hats are the way forward. I would wear a wrag for the run, and then get rid once my head got wet, keeping just the neoprene hat
For my first Tough Guy people were raving about long merino socks. This was a huge mistake! Not only wear they instantly soaking and heavy, they also made my feet too small which meant I had double the reasons for cold wet feet and even more chance of getting crippling calf cramp (which I did).
Wind breakers: I've seen people use wind breakers pretty successfully. I've never tried it, but when you are freezing cold and that Tough Guy wind whips through you, anything to stop that is a help.
Hydration packs: there are water stops on course, and spectators can easily follow you, however, carrying your own water or gels will never hurt, it depends on how fast you're planing on going. The longer you think you may be out there, the better prepared to look after yourself I would advise.
Merino hats. I think I've covered merino pretty well here... it's a no from me.