SSL and Domain Mapping Plugin issues

I'm having issues forcing SSL on my multisite site. The main site is http://www.swingsetsminnesota.com. An example of a subsite is http://swingsetshouston.com/. All the sites have been working fine over http. I've checked and I can load them over https, but I can't force them to https. I added some code to .htaccess that I found here. That successfully forced the main site to ssl, but I got a too many redirects for the subsites. I'd cleared all the caches beforehand (wp rocket, siteground, sucuri).

The subsites are in virtual folders mapped to domains that are parked at Siteground.

The plugin tells me to use the Sucuri IP for the sites and that's what I have set up in the Control Panel at Siteground. The A record of each site points to Sucuri.

I talked to someone on chat last evening and he said that the site should have a dedicated IP. I'm fine with getting that, but after looking over the directions again, I'm a bit confused. It seems like parked domains wouldn't use the A record/dedicated IP approach, so I'm not sure what to do now.

Just checked in GoDaddy and am realizing the setup is a bit confusing. swingsetsminnesota uses the Siteground nameservers. The other sites have their DNS at GoDaddy and their A records point to Sucuri. I'm guessing this is the source of the issue, but I don't know what to do to fix it. Can you help?

We want to keep Sucuri, but I'm thinking it might not be necessary to cover all the sites if we had a dedicated IP - probably covering the main site would be enough protection?

If you can give me the steps to use to set this up correctly, it would be much appreciated!