If you wish to have your OSPF traffic carried across a WAN encrypted, you definetively need to use GRE tunnels: IPSec allows only unicast traffic, whereas GRE IPSec allows multicast and broadcast.
If i have understood well, from your router's configuration, you are trying to setup a tunnel L2L with IPSec on a WAN link. It will carry only unicast traffic. OSPF will not be carried.
However, you might decide to encrypt only the traffic from the LANs and leaving the OSPF traffic to travel unencrypted across the ISP network. This is definetively a design choice.
The config i have attached in my previous post achieves this: only traffic between LAN is encripted. Routing traffic would be sent across the ISP network unencripted (i used static routes, however routing interfaces belongs to different networks and their traffic is not considered interesting for the tunnel). In this way, without GRE, you can encrypt your LAN traffic (assuming you haven't appications requiring multicast) and at same time have your OSPF working. The drawback is that your routing traffic is flowing clear.
Hope this will help
