Suggestions for fitting commutative diagram onto page

Question

I'm trying to fix some hbox errors in the following commutative diagram. Note the symbol strings are simplified here, but what is written is the actual length:

\documentclass{amsart}
\usepackage{tikz-cd}
\begin{document}
\begin{eqnarray*}
\begin{tikzcd}
BAAAAAAAAAAAAAAAAAAAAAAAAAAAA \ar{r} \ar{rd}  & CAAAAAAAAAAAAAAAAAAAAAAAAAAAA   \\
AAAAAAAAAAAAAAAAAAAAAAAAAAAAA  \ar{u}  \ar{r}  &DAAAAAAAAAAAAAAAAAAAAAAAAAAAA \ar{u}
\end{tikzcd}
\end{eqnarray*}
\end{document}

This gives hbox errors (140p or so) and I'm trying to fix it. My first attempt was the following:

\documentclass{amsart}
\usepackage{tikz-cd}
\begin{document}
\begin{eqnarray*}
\begin{tikzcd}
AAAAAAAAAAAAAAAAAAAAAAAAAAAAA  \ar{d} 
\\
BAAAAAAAAAAAAAAAAAAAAAAAAAAAA  \ar{d}  \arrow[bend left=60]{dd} \\
CAAAAAAAAAAAAAAAAAAAAAAAAAAAA  \\
DAAAAAAAAAAAAAAAAAAAAAAAAAAAA  \ar{u}
\end{tikzcd}
\end{eqnarray*}
\end{document}

Here the curved arrow goes through another entry and I'm not sure how to fix that. But there might be a better suggestion anyway. (I don't really want to define four new symbols for the four entries.)

Answer 1

One of possible ways is break your long expressions into two line. For example by use of multlined math environment defined in the mathtools package:

\documentclass{article}
\usepackage{mathtools}
\usepackage{tikz-cd}
%---------------- Show page layout. Don't use in a real document!
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.15pt}
\renewcommand*\ShowFrameColor{\color{red}}
%---------------------------------------------------------------%

\begin{document}
\[
\begin{tikzcd}[sep=large]
\begin{multlined}
    BAAAAAAAAAAAAA \\
    AAAAAAAAAAAAAAA
\end{multlined} \ar{r} \ar{rd} & \begin{multlined}
                                    BAAAAAAAAAAAAA \\
                                    AAAAAAAAAAAAAAA
                                \end{multlined}   \\
\begin{multlined}
    AAAAAAAAAAAAAA \\
    AAAAAAAAAAAAAAA
\end{multlined} \ar{u} \ar{r}  & \begin{multlined}
                                    BAAAAAAAAAAAAA \\
                                    AAAAAAAAAAAAAAA
                                \end{multlined} \ar{u}
\end{tikzcd}
\]
\end{document}

(red lines shows text borders)

Of course, you can use other amsmath environments as are aligned, gathered, split, ...

Addendum (1): Remarks/response to your comment:

Sorry, but we haven't any information about real content of your diagram. However, from my (poor) knowledge of math (it is only my every day tool), any math expression can be broken into two line. If this is not a option for you, than you have the following options:

• use smaller font,
• locally enlarge text width,
• rotate diagram to landscape orientation.

Anyway, I would stick with suggested solution.

Addendum (2): A example of ugly diagram without split math expression:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                positioning}
%---------------- Show page layout. Don't use in a real document!
\usepackage{showframe}
\renewcommand\ShowFrameLinethickness{0.15pt}
\renewcommand*\ShowFrameColor{\color{red}}
%---------------------------------------------------------------%

\begin{document}
\[
\begin{tikzpicture}[
node distance = 8mm and 1mm,
every edge/.style = {draw, -{Straight Barb[scale=0.8]}, semithick}
                    ]
\node (a) {AAAAAAAAAAAAAAAAAAAAAAAAAAAAA};
\node (b) [below right=of a.south] {BBBBBBBBBBBBBBBBBBBBBBBBBBBBB};
\node (c) [below left=of b.south]{CCCCCCCCCCCCCCCCCCCCCCCCCCCCC};
\node (d) [below right=of c.south] {DDDDDDDDDDDDDDDDDDDDDDDDDDDDD};
%
\path   (a) edge    (b)
        (a) edge[out=0, in=15, looseness=3.4]     (d)
        (c) edge[bend left]     (a)
        (c) edge    (d)
        (d) edge[bend right]    (b);
 \end{tikzpicture}
\]
\end{document}