Vertically aligned subfloat caption prevent wrap

I have searched around for this but couldn't figure out the solution for my particular document.

Using this answer I have placed two images of different width side by side.

I would like the text of image (a) to not wrap. Ideally, I would like the image to be centered above the non-wrapped caption.

MWE

\documentclass{article}
\usepackage{graphicx}
\usepackage{subfig}
\begin{document}
\newsavebox{\myimage}

\begin{figure}
\centering
\savebox{\myimage}{\hbox{\rule{150pt}{150pt}}}% Store largest image
\subfloat[First caption text is a bit longer and wraps.]{\usebox{\myimage}} \quad
\subfloat[Second fits on one line.]{\raisebox{\dimexpr.5\ht\myimage-.5\height\relax}{\rule{100pt}{20pt}}}
\caption{This is a figure.}
\end{figure}
\end{document}


Just add some space on the side of the larger image. This will make the caption not wrap:

\documentclass{article}

\usepackage{graphicx,subfig}

\newsavebox{\myimage}

\begin{document}

\begin{figure}
\centering
\savebox{\myimage}{\hbox{\rule{150pt}{150pt}}}% Store largest image

Above I used \quad on either side of the left image. For more options, see What commands are there for horizontal spacing?