Hello,
I do not have a configuration guide for third parties, but had a similar scenario with Mikrotik on the remote side. It is working ok. The first question:
are you using certificates for authentication between the peers? it is mandatory when one of peers the has DAIP.
1800 SMB is centrally managed or locally?
The basic flow for cert authentication is export de CA certificate from checkpoint and import it on cisco side. Then on cisco side create a csr, export it and sign it on CheckPoint side. Use this signed certificate on Cisco side for authentication with this VPN.
For 1800 centrally managed sk109139.
For 1800 locally managed sk112213
These two sk's show the configuration between checkpoint devices. But the same flow should work for third parties. In our case it worked. HTH
Regards