I believe the norm is to go commando, one of the clones will be alone later to confirm with piccies - be grateful they don't cater for fatties else I'd oblige
Whatever I want to wear at the other end of the journey... Most often a pair of jeans and a shirt nowadays! Mind you, last year coming back from London in the summer (remember those?) it was usually shorts and a t-shirt with the 'Stich pockets full of ice from the offy.
Funnily enough, I just pulled that big warning label off the inside of mine today as I packed it.......it says that you should always wear stuff under it 'cos it's made of material that heats up and could/will burn you with friction heat.....
I just chuck it on over what I'm wearing, that's the whole idea surely??