No, that should be it. Only thing to remark is to leave the proxy id's alone. On routebased juniper to routebased juniper you don't fill thim in. When both sides are all zeros they match and phase II can party. Don't know what happens when you do use proxy id's and the source is not within the range of the proxy id. Interesting to find out!!
I think only the ISG;s and NS 5K support this. Alternative might be L3 redudancy. OSPF with different costs or VRRP. Didn't try the last one, dont't know if it's possible to place two interfaces from one device in a VRRP group.