If your network team is an particular area, put all members of the network team in a specific subnet, like a /24 or smaller.
You also may like to consider getting a linux box. One of the main function is for reverse-telnet into your appliance from the outside.
You create an ACL on your appliance that only people in the subnet is allowed access to the appliances.
Disable telnet and enable SSH. Make sure you don't use simple passwords.
RADIUS and TACACS ... very important. Only way to gain access to your appliances is using their Windows login.
