I have a single DNN install (4.8.1) and multiple parent portals installed using full domain names on a single ip address on IIS 6.

Some of these portals might need ssl secured pages like for shopping carts. Because of the limitations I have, I am looking for possible solutions and wanted if they can work:

FIRST SOLUTION:
1- master portal (say domain1.com) has ssl cert installed at secure.domain1.com which will be used as a shared cert for other portals.
2- Second portal as in domain2.com. (aliases = domain2.com and www.domain2.com)
3- want to have the other portals use that cert for their secured pages. I know how this is done in regular none DNN sites using virtual folders as in secure.domain1.com/domain2/.... which points to domain2.com root folder in the case of a regular IIs site.
4- Can DNN support a similar setup? What about the SSL Redirect product, can it help?

SECOND SOLUTION:
1- have each domain or portal get its own ssl cert and because they are all on the same ip address, install each on a different port. While some people say that's not recommended, I don't see anything wrong with this other than a port number showing in the url. DNN will redirect to the proper url/port.
2- Does DNN support this setup?

again some people might have security concerns. If they do, they should give specific concerns.

The implemeted setup will be disclosed to site owners and if it's OK with them, I think it will work for everyone.

Ideas?