Add to ~/.bashrc on client:

tmosh() {
  mosh --no-init $1 -- tmux new-session -ADs main
}  

Add to ~/.bashrc on server:

exit() {
  if [[ -z $TMUX ]]; then
    builtin exit
    return
  fi

  panes=$(tmux list-panes | wc -l)
  wins=$(tmux list-windows | wc -l) 
  count=$(($panes + $wins - 1))
  if [ $count -eq 1 ]; then
    tmux detach
  else
    builtin exit
  fi
}

References:

• https://arslan.io/2019/01/07/using-the-ipad-pro-as-my-development-machine/