Caddy Reverse Proxy Setup

I need help setting up Caddy as a reverse proxy for several websites hosted on virtual machines behind a NAT router. Each site uses its own domain name.

Requirements:
- Caddy configuration to route traffic to multiple VMs.
- Access via private network addresses.
- Proper handling of domain names for each site.

Ideal Skills and Experience:
- Proficient with Caddy and reverse proxy setups.
- Experience with NAT and private networking.
- Strong understanding of domain name configuration.

Please provide your experience and approach.