Jump in DMZ

So we are looking for a solution to use RDM in remote support situations where we might not have access to our VPN.
Is the Jump server secure enough to sit in a DMZ and we would have an external IP on that server to connect to - but how is the authentication handled to start RDM to the Jump server? Also, on the ports tunneled through the firewall are they all of the individual communications ports for each protocol I assume?

I like the concept of the Jump server but just not 100% confident on how it would work when installed and running in a DMZ.

Thanks!