We do that. I can't tell you all of the specifics that our IT did to make it work.
But at a high level we purchased a SSL certificate for the URL that we wanted to use. That was installed on the QS server and the QMC was updated in the virtual proxy whitelist and there is a place to enter the SSL Thumbprint in the Proxy settings.
I know that the ports had to be opened in the firewall that QS uses.
And the setup will be a little different if you are in the DMZ or in the network. But that is all IT stuff that I didn't get too involved in.
So now we access the QS server and QMC from anywhere just using the browser.
There has to be documentation on the Qlik site that details how to do this.
In a nutshell, QlikSense provides Web Server[s] that are accessed by client web Browsers.
So you need to put a QlikSense Web Server in your DMZ, the same as you would for any other web site you host on server[s] in your DMZ including opening up required firewall ports.
The first thing I suggest you do is have a word with the people who administer your DMZ, firewalls & web servers, and from them find out what internal processes / policies you need to adhere to. Especially with regard to authentication and security.