使用“\enlargethispage”时如何向下移动页脚？

Question

\clubpenalty和\widowpenalty是可以设置的参数，有助于防止前一页或下一页出现单行。但是，有时，我们可能会在下一页上看到两三行，而新部分则在它们之后开始。在这种情况下，最好将这两三行移到上一页。典型的解决方案是使用\enlargethispage{<added space>}命令，如果没有页脚内容，该命令会很有效。当有页脚内容（例如，页码）时，添加的行将与其重叠，如下例所示

我想要的是一种系统的方法来移动页脚，移动的量恰好等于<added space>文本和页脚之间的边距，就像正常的（未放大的）页面一样。

\documentclass[10pt]{book}

\usepackage[a4paper]{geometry}

    \geometry{twoside=false, showframe=true}

    % ===== Horizontal =====
    \geometry{inner=0.87in,outer=0.87in}
    \geometry{includemp=true,asymmetric=true,bindingoffset=5mm}
    \geometry{marginparsep=0mm, marginparwidth=0mm}


    % ===== Vertical =====
    \geometry{bottom=19mm,vmarginratio=3:5}
    \geometry{includehead=true, includefoot=true,headheight=8pt, headsep=14pt,footskip=5mm}


\usepackage{fancyhdr}
% BEGIN_FOLD
    \fancypagestyle{plain}{
        \renewcommand{\headrulewidth}{0pt}
        \fancyhead{}
        %
        \fancyfoot{}
        \fancyfoot[C]{\thepage}
                            }
    \setcounter{chapter}{0}
% END_FOLD

\usepackage{blindtext}


\begin{document}

\pagestyle{plain}


\blindtext[7]


Mauris lacinia lorem sit amet ipsum. Nunc quis urna dictum turpis accumsan semper.
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Etiam lobortis facilisis sem. Nullam nec mi et
neque pharetra sollicitudin. Praesent imperdiet mi nec ante. Donec ullamcorper, felis non sodales com-
modo, lectus velit ultrices augue, a dignissim nibh lectus placerat pede. Vivamus nunc nunc, molestie ut,ultricies vel, semper in, velit. Ut porttitor. Praesent in sapien. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Duis fringilla tristique neque. Sed interdum libero ut metus. Pellentesque placerat. Nam rutrum augue a leo. Morbi sed elit sit amet ante lobortis sollicitudin.

\enlargethispage{1.7\baselineskip}
After adding these two lines using \verb|\enlargethispage{1.7\baselineskip}|, its overlaps with page numbering. How can we shift the footer downwards with an amount equal \verb|1.7\baselineskip|?

\end{document}