Tacacs per vrf no supported on my router, does a gre tunnel would work?

Question

Hi,
Basically the problem is that I am working with old routers, checked already on feature navigator an the following commands are not supported on the router to communicate to a TACACS server that resides on a vrf:
Configuring Per VRF for TACACS+ Servers: Example
The following output example shows that the group server tacacs1 has been configured for per VRF AAA services:
aaa group server tacacs+ tacacs1
server-private 10.1.1.1 port 19 key cisco
ip vrf forwarding cisco
ip tacacs source-interface Loopback0
ip vrf cisco
rd 100:1
interface Loopback0
ip address 10.0.0.2 255.0.0.0
ip vrf forwarding cisco
Basically I can not support all the above, however I was thinking of bypassing the command creating a GRE tunnel, I just need a confirmation if the following would work, if not I would appreciated that someone can point me into a better direction:
ON BRANCH ROUTER:
int l0
ip add 1.1.1.1 255.255.255.0
no shut
int tun10
ip add 2.2.2.1 255.255.255.0
ip vrf forwarding cisco
tun so l0
tun dest [ip add of router directly connected to tacacs server]
ip tacacs source-interface l0
tacacs-server host 10.10.10.1
tacacs-server key 7 cisco
ON REMOTE ROUTER:
int l0
ip add 3.3.3.3 255.255.255.0
no shut
int tun10
ip add 2.2.2.2 255.255.255.0
ip vrf forwarding cisco
tunn so l0
tunn dest [ip add of branch router]
Attached is some real information, the ip address of the real tacacs server is 10.20.30.61.

Answer 1

Thanks for the response but I post the question after knowing that, I already checked on Feature Navigator that THIS IS NOT SUPPORTED for my router, at the end of my configuration I am purposing a workaround using a tunnel to bybass the nonsupported configuration.
My question to you is, does a configuration with gre with vrf can work instead of the nonsupported configuration?
I know that the alternative is to run Radius but it is more paperwork to do than trying to implement a solution with the current IOS.
Thanks and sorry if I didn't make self clear at the beginning of my first post.