Remote Console

[Grant Peel]

Hi all,

I have asked this question before, so if it looks familiar ...

I am hoping all the reading I have done over the past few weeks makes this 
instance of the qeustion clearer.

Background:

1 Dell 24 Port Switch, WAN connection to my ISP.
5 Dell Serers, each with 2 NICs.
    1 NIC on each connected to SWITCH - VLAN 1 -WAN (Many different IP's).
    1 NIC on each connected to SWITH - VLAN 2 -LAN (192.168.0/24)

    Each Server has 2 Serial ports, unused.
    Each Server has 2 USB ports, unused.

All servers running FreebSD
    2 Running 4.10
    1 Running 5.2.1
    1 Running 5.4
    1 Running 4.4 (Slave3 Nameserver only).

I am ~ 120 miles from the server cage these are located in. So traveling to 
there is a real pain.

I have been reading everything I can find on consoles, ttys, blackboxes, 
Lantronix serial cables etc, etc ,etc ,etc ...

What I am looking to do, is to connect all the servers to a device, or, 
daisychain them together so that even if I reboot a broken machine, I can 
still get to a "boot ?" prompt, not to mention single user mode and normal 
ssh shell prompt. (of course I already have the latter through IP when the 
machine boots correctly.

So my question is, can a machine be made to still be remotely accessable 
(any method), when file systems are not mounted, or, kernel not loaded? If 
so, using what setup?

-Grant