I currently have:

6.0SP4 production server
6.0SP2 Border Manager Server (3.7)
192.168.1.0 network

Because of all the VPN problems I need to switch my private network address scheme

I could upgd production to 6.5 and make the IP changes there in Remote Manager (DHCP is on this server, would I have to remake all of the subnets there?) That is the only thing I can think of that would be out of the ordinary on this server. On the BM I believe I would have to apply SP4, upgd to BM 3.8, upgd to 6.5, apply 6.5sp1, then change IP address. If I do that will I:

1. Loose any of my VPN settings, filter settings, proxy settings or anything else that will cause me great distress in BM?
2. Will my ip address change be all done with Remote Manager or will I have to configure several things in BM by hand (if so what would they be)?

I don't have extra servers laying around so I am in a position where I have to know what to do the first time and it has to work. I greatly appreciate any help!