I have successfully used this plugin to secure admin access to my site on shared hosting without paying for dedicated IP and certificate.
Not recommended if you want your clients to use the admin since they need to allow a mismatched certificate; only you and people who trust you will do that.
I am the only person accessing the admin so this is no problem for me.
The details are here:
https://wordpress.org/support/topic/secure-admin-access-on-shared-hosting
Saves a lot of money and trouble!
(I did not try any other features.)