It seems a little fruitless to use bindshells with your backdoor. The only exception I can see is if you are on the same subnet, and your backdoors are ran with admin privileges. The main issue I have is the inability to bypass NAT when using bindshells.
Why not have them reverse connect? Doing so takes away three problems at once: having to be ran with admin privileges to listen, only has to comply with outbound firewall rules, and as mentioned before, bypasses NAT restrictions.
you can use any back door you like
the point is that the bd will connect to the mannager
to find where and if it should connect, you could use this with ant bd
EvilVnc(RCBDM) comes to mind
Edit:
a few get requests to a web server are not likely to be spooted by anyone
the manager just tells the bd where and if to connect
Edit 2:
This is a manager for reverse connection back doors
its simple the bd connects to the manager and asks
for its info (from the log file) then connects to the ip\port you tell it to