How to NAT in either direction on two interfaces

TIS

We're trying to NAT because we have a network with a 192.168.0.0/16 network and a site we're trying to connect to has a network of 192.168.142.0/24. Unfortunately, we have no control of the remote site and therefore can't do anything to their network. All the configuration needs to be in the Watchguard to make it work. We think we have a solution logically, but we can't seem to make it work in the Watchguard. Could someone help please? A drawing of what we are trying to do is in the link below.

[https://uksouth1-mediap.svc.ms/transform/thumbnail?provider=spo&inputFormat=png&cs=fFNQTw&docid=https%3A%2F%2Ftisfireandsecurity-my.sharepoint.com%3A443%2F_api%2Fv2.0%2Fdrives%2Fb!g90GiLP5Ck-JOuwrRShOiB-1pymwTdpNgivYZXlAcsP2cSdWjVUYS5rzau1KfZb1%2Fitems%2F01NKD7BMVDIGDYIN22FJE2UDJ7RRDU4CRI%3Fversion%3DPublished&encodeFailures=1&ctag=%22c%3A%7B848741A3-5A37-492A-AA0D-3F8C474E0A28%7D%2C2%22&srcWidth=&srcHeight=&width=2256&height=1231&action=Access](https://uksouth1-mediap.svc.ms/transform/thumbnail?provider=spo&inputFormat=png&cs=fFNQTw&docid=https%3A%2F%2Ftisfireandsecurity-my.sharepoint.com%3A443%2F_api%2Fv2.0%2Fdrives%2Fb!g90GiLP5Ck-JOuwrRShOiB-1pymwTdpNgivYZXlAcsP2cSdWjVUYS5rzau1KfZb1%2Fitems%2F01NKD7BMVDIGDYIN22FJE2UDJ7RRDU4CRI%3Fversion%3DPublished&encodeFailures=1&ctag=%22c%3A%7B848741A3-5A37-492A-AA0D-3F8C474E0A28%7D%2C2%22&srcWidth=&srcHeight=&width=2256&height=1231&action=Access)

Bruce_Briggs

I don't see anything when I click on your link.

How are these 2 networks connected?

Any reason why you need a /16 subnet for your site?