quite devious: if prefix, p is used, tell ssh to use custom TERM value; also more features for zsh

tmux.conf

@@ -16,7 +16,7 @@ bind + resize-pane -U 5
 bind e choose-session
 bind t command-prompt -p "attach pane to:"  "join-pane -t :'%%'"
 bind y command-prompt break-pane
-bind p command-prompt -p "ssh:" "new-session -As '2-ssh'; new-window -n '%1' 'ssh %%'"
+bind p command-prompt -p "ssh:" "new-session -As 'ssh'; new-window -n '%1' 'TERM=screen ssh %%'"
 bind -n M-w next-window
 bind -n M-q previous-window
 bind -n M-j next-window

zshrc

@@ -75,10 +75,10 @@ PROMPT3='%b%f?%(!.%F{red}.%F{black})#%f%b '
 PROMPT4='%b%f+%N:%i%(!.%F{red}.%F{black})>%f%b '
 precmd.title() {
     case $TERM in
-        xterm*|rxvt*)
+        st*|xterm*|rxvt*)
             printf "\033]0;%s@%s\007" $USER ${HOST%%.*}
             ;;
-        screen*|tmux)
+        screen*|tmux*)
             printf "\033k%s@%s\033\\" $USER ${HOST%%.*}
             ;;
     esac