Hello Folks,
I'd appreciate some tips and comments.
My plan is as follows:

1.Use source based routing on CCR1 to mark upstream packets with src IP x.x.x.x/x on ingress interface X and forward to another Microtik CCR2.
2. Customers are shown a page to advise they are in breach of a fair usage policy and need to accept it by clicking OK. They can't surf until they do this.
3. Ideally once they accept they should no longer enter the walled garden but not sure if this is possible.
4.The packet is then routed back to CCR1 where it is not marked (different interface) and routed to our upstream peer.

I can figure out step1 but I'm not sure what the best practice is for steps 2 and 3, from what I've researched I should be able to use the hotspot and walled garden method, however customers will already have an IP address and they will need to be auto logged in. Another possibility is use an advertisement method feature of the hotspot. I imagine someone must be doing this already.

Look forward to the comments,
Chris.