Cisco Switching/Routing :: 1721 / Change Remote Site Network Configuration With / Without Losing Connection?

My company just assumed management of a remote entity.  The network has several misconfigurations and I need to make some network modifications from my office w/o losing access or incurring lengthy outage to the clients.  The network consists of 1721 router and  three 2960 switches.
 
- I only have access to the router from the Internet.  I telnet off the router to the 3 switches.
 
The site uses a single class C 192.168.1.0 / 24.  The router is running RIPv2 even though this is the only network.  The prior network person (contractor) set up separate native vlans on each switch and all the ports are defined as Native trunk and access are defined to the VLAN interface  assigned to the switch.  So of course the logs are flooded with Native VLAN mismatch,  Each 2960 switch is a VTP server but has no VTP domain.  
 
basic network layout:
 
Internet  => Eth [Cisco 1721] => Fa 0 192.168.1.254  ==> [SW1]
 [SW1]
 interface Vlan1
no ip address
no ip route-cache!interface Vlan220ip address 192.168.1.219 255.255.255.0no ip route-cache

[code]....
 
!interface GigabitEthernet0/1description SW2 Gi0/1switchport access vlan 204switchport trunk native vlan 204!interface GigabitEthernet0/2switchport access vlan 204switchport trunk native vlan 204!interface Vlan1no ip addressno ip route-cache!interface Vlan204ip address 192.168.1.224 255.255.255.0no ip route-cache Normally, I would assign the current 192.168.1.254 to a subinterface to Router Fe 0/0 but with each switch having its own native VLAN I am afraid I will lose connectivity to the downstream switches -- my only access is telnet off the Cisco1721 Router.