I compete in hillclimbs.
I use a Proban suit as they are a lot cooler.
I wear a Nomex balaclava as it keeps my ears flat and helps to get helmet easily on and off!
High Sparco racing boots,Nomex long gloves,pure cotton full sleeve shirt and Nomex or cotton socks,I prefer cotton as I find the Nomex socks slip down when walking around paddock.
I think as long as the undergarments are not of synthetic material it's OK.
Many don't wear any vest but as someone said the suit would soon get pretty grim inside,and I think it's best not to wash the suits too often,probably 3-4 times a year?
Lister