Workaround to CIDR overlap using site-vpn between AWS and Cisco Meraki on DX?

We are trying to setup a site-to-site VPN from AWS to customer Data center running Cisco Meraki Gateway. This shouldn't be much of hassle setting up and getting the tunnels up, however the issue is we are both on overlapping subnet CIDR.

The problem is that AWS transit gateway/site-vpn setup doesn't allow SNAT/DNAT and in this case the customer gateway (Meraki) also doesn't support SNAT/DNAT as a workaround.

I looked up setting up Openswan to SNAT/DNAT but the https://aws.amazon.com/articles/connecting-cisco-asa-to-vpc-ec2-instance-ipsec/ mentions setting up NAT on the destination side as well.

What are the some of the workarounds I can do to get this tunnels up and running?