Batman adv and multi wan meshing

Hello community,

I'm currently playing around with batman adv. I would like to deploy it in a dynamic environment where I have sometimes only one gateway and sometimes multiple gateways with LTE connections to different ISPs. Sometimes some wan connections would be down so I would need a solution that automatically changes to one of the gateways that have actual access to the www. Now, in my little test setup, I've got a Teltonika RUT950 as a mobile wan gateway, a Ubiquiti Unifi AC Mesh pro as another wan gateway and a couple of Unifi AC Mesh APs as nodes. The two gateways are configured as server/uplinks, whereas the two nodes are configured as clients. My understanding is that batman adv is trying to advertise the nearest DHCP server, although it's not aware if that gateway has actually access to the www. My test setup works fine as long as the chosen DHCP server has www access. If I take that gateway offline and put the other gateway online, it won't reroute. (I assume because batman adv is level 2 and thus it's none of its business?)

So now, how would I go about this? Would I need to solve this issue on level 3? On top of batman? I can post my configs but I assume my mesh works as intended. I think I need more of a push into a certain direction because right now I'm not sure if wan failover/switch to a different gateway is something that batman adv is capable of. I'm really new to batman adv and I'm still trying to wrap my head around it.

Thank you so much for taking the time to read my rather long question.