ICX multiple interfaces to default route

[sparkis_greenbr]

3 switch stack. Using 1/2/1 2/2/1 3/2/1 SFPs as uplinks to firewall. Trying to figure out best way or any way to get all my internet traffic out to any of those ports. 
I can map a single destination network to mult int's and the switch can do a little load balancing RR, but I cannot map the default route to multiple interfaces. tried moving them to vlan and using ve but cannot route default route to ve int. 

So does anyone have any suggestions on how to configure the default route to be available via three uplink ports? This is all on one stack. If one of those interfaces went down, I want internet traffic still routing out.