Where you have a connection to a site that host multiple servers / RMA's but only wish to allow access through the external firewall on 1 port (1055)you would have to query the individual agents via a reverse proxy service or possably a Master RMA bridgehead that would pass the test requests to the the individual agents and the responses back to the central hostmon machine.
Is there anything currently being developed like this??
I don't think this feature can be implemented in nearest versions.
On the other hand single RMA can monitor all servers in the network. So, probably you don't need many agents instaled behind firewall?