@jmeyer Having a FOG server with a dual nic is a standard and supported configuration for installing FOG.
There are a few things you need to know/do before installing FOG.Know the linux kernel names of your network interfaces. You can see this by using the following command ip a s Identify the name of your business network interface and your imaging network interface. Document these names. Make sure your imaging network interface is configured for a static IP address. FOG does not like having the imaging network interface IP address changing once FOG is installed. Make sure your business network interface has a default route defined so that it can get to the internet. Confirm that your fog server has internet access. Make sure your imaging network interface does not have a default route defined.
Now use the git method to download the installer files onto your FOG server.
Install FOG. During the installation process you will be prompted for the linux name of your imaging network interface. Key that in when requested. You will also be prompted to if you want to install a dhcp server. Answer yes to this. The fog installer will only bind the dhcp server to the imaging network interface leaving your business network interface alone during the installation of FOG. There will be no conflicts on the business side since fog will only focus on the interface you said that is your imaging network.