I’m trying to figure out if it is possible to colocate our infrastructures to other ISP in our region.
We want to add their SSID to our Mikrotik Routers and redirect all trafic to their office?
what?
Yes, I have investigated this for the same reason you have.
Simply add the Virtual AP, attach it to a VLAN interface, tagged with a different VLAN ID, and set up a PtP backhaul or VPN tunnel to their office, and send all of the VLAN marked traffic to them…
I believe you have to "bridge’ the VAP and the VLAN interface, by the way.