L2 bridging between two Balance and DHCP servers at each end.

Hello crowd,

having 2 locations - with each their Balance router and a L2 SF VPN in between. Offcourse having an IP scope to cover for both locations due to bridging.
But sametime having a wish to run a site specific DHCP server at each end (allocating a subnet of the total IP scope) to be able to verify where traffic on the network is coming from.
Due to L2 nature of the bridging - the DHCP servers do actually hand out adresses across sites.

Is there any way to block DHCP request from travelling accross the L2 tunnel? (Or will i have to rebuild the whole setup as a routed tunnel with individual IP scopes per site?)