[MarioL]

It seems I wasn't that clear, let me explain this a bit better.

When you Edit the "ISP Link", the next hop has to be the gateway, but then you have the "Advanced" tab, where you can add "Monitored hosts".

So leave your config as is, but do the traceroutes to get the next hops after your edge routers for both ISPs, or some DNS servers or something "fairly close that accepts ICMP".

Create these hosts objects with their IP addresses and then add them in the Advanced tab.

Hope that helps.