[Tex/LaTex] combination of macron and breve diacritics

Question

I try to combine the macron and the breve accent. This post already helped me to get a good adaptive macron, and the \u command produces a nice breve, but I have problems combining them.

How can I combine them cleanly or – better – how can I draw a breve like \u produces combined with the \supersmartmacron macron (see link)?
Thank you a lot for helping me out!

PS: I am aware of \textbrevemacron from the tipa package, but it's just ugly in combination with \usepackage{mathpazo}.

Edit 1

Thanks to Alenanno I found a good way for stacking diacritics in this post:

\documentclass{article}
\usepackage{stackengine}
\begin{document}
\renewcommand\stacktype{L}
\stackon[3pt]{\={a}}{\u{}}
\end{document}  

This produces nice combinations of the \= and \u diacritics (using the selected font, which \textbrevemacron does not → "ugly" – sorry for not pointing that out), but: Especially with the \i it gives a rather oversized symbol. That is what \supersmartmacron does, it creates a macron which length depends on the character width.
Is there a way to scale \u down a little bit?

MWE for the problem:

\documentclass{article}
\usepackage{stackengine}
\begin{document}
\renewcommand\stacktype{L}
\stackon[1.5pt]{\={\i}}{\u{}}
\end{document}

Thank you!

Edit 2

Another problem of the solution with stackengine is that the distance needs to be specified. The above example works well with fontsize=12pt only, for greater or smaller symbols it's necessary to adjust the value.

Answer 1

You may want to build it by hand:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{mathpazo}

\DeclareRobustCommand{\brevemacron}[1]{%
  \leavevmode
  \vbox{\offinterlineskip
    \ialign{\hfil##\hfil\cr
      \u{}\cr\noalign{\kern-1ex}
      \={}\cr\noalign{\kern-1ex}
      #1\cr
    }%
  }%
}

\begin{document}
\brevemacron{a}\u{a}\={a}

\brevemacron{a}\brevemacron{e}\brevemacron{\i}\brevemacron{o}\brevemacron{u}

\brevemacron{A}\brevemacron{E}\brevemacron{I}\brevemacron{O}\brevemacron{U}

\end{document}