Sorry if this is a noob question, had a good search and can't find what I'm looking for which usual means I'm doing something in totally the wrong way!!

I'm using routing marks to manage traffic out to different ISP's. Once of this is via a PPPOE connection which gives me a dynamic route to their next hop. Ideally I'd to add a routing mark direct on this. In the past I have been over-riding this by setting a matching static route with a lower distance and putting the routing mark on here. However my ISP has now taken to changing the next hop IP at seemingly random intervals making this approach fail.

How should I be doing it?

Cheers

You can use routing filters to change route parameters when it's created: In this example, original distance 10 is what's used to match the right route.