You could possibly spin up another DC, make it RODC if you prefer, and point the Meraki MX to it for authentication therefore taking the workload off of your prod DCs. I believe you could set the logging on the new DC to be reduced to hopefully help with the overhead like others have said but keep the logging as is on the prod DCs. Kind of overkill to spin up another DC for just this but it may help. ... View more

I agree with  mmmmmmark that it may not be the best design if relying on a single MX / Internet connection at the branch office or HQ. A RODC would be ideal at the branch. You could go with redundant MX and Internet connections to try and limit exposure to a failed connection but it may not be worth the cost, depending on your needs. ... View more