I'm in exactly the same boat as you (except we're at PCI level 2).
tmux on my local machine does me fine. And as loading tmux inside of tmux is pointless, I don't need to copy configs across.
though what I do have is a number of cheat sheets for each type of server, so I have copy and paste code (most of it is simple enough stuff, but sometimes having a visual reminder is helpful when you're up against tight, stressful, deadlines)
tmux on my local machine does me fine. And as loading tmux inside of tmux is pointless, I don't need to copy configs across.
though what I do have is a number of cheat sheets for each type of server, so I have copy and paste code (most of it is simple enough stuff, but sometimes having a visual reminder is helpful when you're up against tight, stressful, deadlines)