Anyone recommend a thermal one piece under suit for sleeping in etc

Not sure about a 1-piece, sounds like a recipe for disaster when you need a pee 😄
I use a Helly Hansen 2-piece thermal under set, have heard Snugpak also offer a good one. There was a recent thread on thermals of you search it up 👍

In reply to Post #1
I would not use a one piece as it has quite a few limiting factors.
To do with bodily functions especially if your in a hurry.

I'm with the other guys here. I would go with a two piece unless you want to strip off everyime you want a crap. There is nothing good about managing a trapdoor in your underwear, particularly in the dark and cold using a portaloo.