Setting template background with multiple .png files

Question

I'm a neophyte to Tex and all of it's forms, though I've used LaTeX in the past. Mostly I've find some thing that someone else created then modified to suit my needs. I've undertaken a project at work to put together a new, custom Beamer theme for my department and, given my neophyte status, have run into a brick wall.

Ultimately, this is what I want:

but, with my beamerinnerthemeViciCustom.sty:

\mode<presentation>

%\setbeamertemplate{background}{
%   \begin{figure}[t]
%   \hspace*{-1cm}
%   \includegraphics[width = \paperwidth]{top_box}
%   \centering
%   \end{figure}
%
%   \begin{figure}[b]
%   \hspace*{-1cm}
%   \includegraphics[width = \paperwidth]{bottom_box}
%   \centering
%   \end{figure}
%
%   \begin{figure}[b]
%   \hspace*{-1.5cm}\vspace*{-1.73cm}
%   \includegraphics[width = \paperwidth]{footer_box}
%   \centering
%   \end{figure}%
%}


% Title page
\defbeamertemplate*{title page}{ViciCustom}[1][]
{

\begin{figure}[t]
\hspace*{-1cm}
\includegraphics[width = \paperwidth]{top_box}
\centering
\end{figure}

\begin{figure}[b]
\hspace*{-1cm}
\includegraphics[width = \paperwidth]{bottom_box}
\centering
\end{figure}

\begin{figure}[b]
\hspace*{-1.5cm}\vspace*{-1.73cm}
\includegraphics[width = \paperwidth]{footer_box}
\centering
\end{figure}%

%   \vskip2cm%
%   \begin{beamercolorbox}[wd = 12cm, leftskip= 3cm, sep = 8pt, #1]{title     page header}
%       \usebeamerfont{title}\inserttitle\par
%   \end{beamercolorbox}%
}
\mode<all>

I get this:

Clearly, I'm nowhere close to what I want. I haven't even attempted to add the logo box. I THINK what I want is to have the images in the \setbeamertemplage{background}{} (which is why I've included it here), but when I have the images there, I get

! LaTeX Error: Something's wrong--perhaps a missing \item.

on line 15 from my .tex file

\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

\title{Here's a thing}

\usetheme{ViciCustom}

\begin{document}

\begin{frame}
\titlepage
\end{frame}

\end{document}

I've found a great response here on tex.stackexchange.com about building a template from scratch but this is drawing boxes with tikz rather than inserting images. Maybe I'm too dense to know how to modify the excellent tutorial presented above?

I'd love some guidance; as a complete newbie to Tex/LaTex/MikTex, etc., I know I need to educate myself some more but I'm incredibly frustrated that I can't even make pictures go where I want them to go.

If you'd like, here's a link to an imgur album with all of the .png files.

Please note that the boxes are representations of what will be in the title slide. In other words, they're not just boxes filled with color.