And another htaccess question!

In this post https://premium.wpmudev.org/forums/topic/htaccess-rewrite-help-needed#post-259038 I explored doing a FIND AND REPLACE on the wp-admin folder so that it would not show in the url bar (strictly for branding purposes).

Now in THIS post I did something completely different on a separate site. I REDIRECTED wp-content to member-content using htaccess and wp-config. Here is the code:

In wp-config:
/* Changes to redirect wp-admin to member-admin folder */

$redirect_url=$_SERVER['REQUEST_URI'];
if(preg_match('/wp-admin/i', $redirect_url)) header('Location: '.str_replace('wp-admin', 'member-admin', $redirect_url));

2. Then replace htaccess for a network that uses easy blogging with this:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteRule ^([_0-9a-zA-Z-]+/)?member-admin$ $member-admin/index.php\?wdeb_on [R=301,L]
RewriteRule ^member-admin(.*)$ wp-admin$1

RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin/([_0-9a-zA-Z-]+).php\?(.*)$ $member-admin/$2\.php\?$3 [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^[_0-9a-zA-Z-]+/(wp-(content|member-admin|wp-includes).*) $1 [L]
RewriteRule ^[_0-9a-zA-Z-]+/(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

It gets me really, really close BUT I get http error messages when I try to upload images. The server company said: "The problem appears to be with half of your site using a custom location - '/member-admin' - while the other half is still attempting to use the default Wordpress location of '/wp-admin'. The upload process does a POST to the async-upload.php script at "/wp-admin/async-upload.php" successfully, then attempts to do a GET to '/private-admin/async-upload.php' to check the status, which is returning an "403 - Access Denied" error."

I was told that "Yes, redirects can handle POSTs as well as GETs. But, depending on how you've coded your RewriteRule, you may need to use the "P" option. See this thread for an example:

http://stackoverflow.com/questions/358263/htaccess-is-it-possible-to-redirect-post-data."

So how would I fix the above .htacess and/or wp-config to take care of this image upload issue?

Points for whomever can help me succinctly with this one, I have been a troll in forums everywhere!