IIS 7 URL Rewrite Only If No File Nor Subdirectory Nor Query String

(I posted this question on StackOverflow because searches for an answer showed related questions on StackOverflow, which got answers and many upvotes. But my question so far earned a downvote and an "off-topic" close vote, so I'm trying asking here where it may be considered more on-topic.)

I would like to do a URL rewrite (or redirecton if need be, like in this answered question), except I would like it only to rewrite/redirect if the requested URL is only the site root (with no files or subdirectories and no query strings).

i.e. I want only requests for TheSite.net to rewrite/redirect to TheSite.net/home.htm, but requests for TheSite.net/FAQ.htm or TheSite.net/sub or TheSite.net/?parameter=yep to not be rewritten/redirected.

I have gotten rewrites and redirects to work such as:

<system.webServer>
    <rewrite>
      <rules>
        <clear />
        <rule name="Rewrite home page to Home.htm" stopProcessing="true">
          <match url="^" />
          <action type="Rewrite" url="/Home.htm" />
        </rule>
      </rules>
    </rewrite>
</system.webServer>

I have also tried <match url="^$" /> and <match url="TheSite.net" />, but those naturally rewrite TheSite.net/?parameter=yep too, and I need it to not do that. Perhaps if there is another attribute of <match> which lets me match empty query string but not if there is a query string (or not match if there is anything is after the slash)?

I'm hoping an appropriate rule could do what I wanted, but my RegEx syntax skills are not up to the task and I haven't found an example of something close enough.

On this site, I see IIS URL Rewrite Module Query String Parameters looks like it might be the sort of thing that could work, though what I want is the opposite – to only rewrite if there is no query string or other content after the domain name in the URL.