.htaccess restrict subdomain by IP - Wordpress Multisite - regex

Question

I'd like to redirect traffic away from a subdomain install of Wordpress Multisite unless it's coming from a specific IP address/range, and without affecting the root domain traffic. Is this possible?
Conceptually, I've been thinking something like this:
# IF we're dealing with the subdomain
RewriteCond %{HTTP_HOST} subdomain\.example\.com [NC]
# AND the user is NOT from our allowed IP
RewriteCond %{REMOTE_ADDR} !111\.222\.333\.444
# THEN redirect them to the root domain
RewriteRule ^(.*)$ http://example.com/$1 [L,R=302]
In other words, restrict access to the subdomain from all traffic that doesn't originate from a defined IP address. I've literally just learned regex and .htaccess for this, so apologies in advance for anything that's glaringly wrong.
The reason I'm not doing this with directory specific .htaccess is that I'm working with a subdomain install of Wordpress Multisite, so there are no directories. It's all in the URL.
Some possible complications that come from Wordpress itself:
Ideally these rules should be added in such a way that they aren't overwritten every time the permalink cache is refreshed in WP.
I'm not sure what RewriteBase / evaluates to, or how it's affecting URIs (if that's the correct acronym) in my file.
EDIT:
Per #Prix feedback, here is the complete .htaccess file I'm working with:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} subdomain\.example\.com [NC]
RewriteCond %{REMOTE_ADDR} !111\.222\.333\.444
RewriteRule ^(.*)$ http://example.com/$1 [L,R=302]
RewriteRule ^index\.php$ - [L]
# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
</IfModule>
# END WordPress
This is Wordpress' Multisite default rules, with my own additions included immediately after RewriteBase /. I incorporated #hjpotter92's suggestion.
The desired affect it to redirect all traffic from subdomain.example.com to example.com, unless it's coming from a specific IP address. This is for a client who's essentially using part of their Wordpress Multisite as a company extranet.

Answer 1

The rule looks fine yes, the only thing I would change is this:
RewriteRule ^(.*)$ http://example.com/$1 [L,R=302]
Into this
RewriteRule ^ http://example.com/ [L,R=302]
As you don't want a 404 on the redirect aside from that given the subdomain share the same DocumentRoot, then yes, it should work as I have tested it myself.
And I hope at this line:
RewriteCond %{HTTP_HOST} subdomain\.example\.com [NC]
You're not adding noise to it like http:// or anything other than the qualified domain name, such as for example intranet\.mydomainname\.com no slash, no http, etc.