Domain Mapping to either http or https

I have a multisite set up to force https on the primary and subdomains via htaccess. But I would like users to be able to choose either http or https if they want to map to their subdomain. Once they do, I want traffic to be forced to whatever they choose. So for example, if they choose https, but a visitor uses http for the URL prefix, I would like it to be forced to https. Currently the Domain Mapping plugin as configured only returns ‘Valid’ in the plug’s Health Status for https, which then maps/routes traffic properly when the https is the URL prefix. If http is used however, it routes traffic to an error page.

How do I get the other options to validate properly in Health Status, and then map/route traffic as above?

All help is certainly appreciated!

Martin

P.S. The htaccess instructions are:

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

RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteRule ^(.*/)?sitemap.xml wp-content/sitemap.php [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]