I have 2 physical sites that are connected by 2 layer 2 connections. One is ASE and the other is microwave. At each site I have 2 Cisco stacks and 2 HA Fortigates. The Fortigates are setup as internal segmentation firewalls and handle all the routing. They are connected using redundant interfaces (Not ideal, but I am limited since they are 300e's). Spanning the vlan across the 2 is not a problem. I have that now and it works fine since the connections are layer 2. Routing and spanning the connections across both sides is where I need some help.
My idea was to create the new vlan on all 4 switches and trunk them (not sure if this will create a problem with stp, but I can deal with that). From there, create a set of redundant interfaces between each of the Fortigates and Cisco's. Create a vlan on the redundant interface and set it up as vrrp with my hq as the primary and my dr site as the secondary. Is this a workable setup, or is there something glaring I am missing? There is an example in the attached jpg.