You can play with routing:

Host                                    Loss%   Snt   Last   Avg  Best  Wrst StDev
1. kheb.queton.naquadah.org              0.0%    47    1.1   2.1   0.3  36.1   5.9
2. netu.vpn.queton.naquadah.org          0.0%    46   74.7 230.8  66.7 2160. 387.6
3. nasya.vpn.dmz.naquadah.org            0.0%    46  129.6 354.1 121.4 1979. 408.9
4. gw.dmz.naquadah.org                   0.0%    46  117.7 390.4 115.6 2064. 453.1
5. abydos.adm.naquadah.org               0.0%    46  122.7 348.9 115.5 1958. 402.3

For people knowing my network arch:

jolinar -> kheb -> netu -> nasya -> othala -> abydos

This means:

laptop (parents home) -> queton gw -> Main VPN server -> DMZ VPN server -> dmz/adm gw -> workstation (home)

Netu is the central VPN server. queton.n.o and {adm,dmz}.n.o are two networks on 2 differents sites. Quite fun !

I use vtun for this.