As Brian rightly suggested SEP will not be installed to printers thereby causing any memory overflow.
You can make a note of your network printers ip address. When you deploy the client package either through the SEPM Console or through the Migration & Deployment Wizard exclude these ip address.
In the SEPM Console you can assign the role of Unmanaged Detector to one of the clients who would monitor the ARP broadcast in your network. In case a new machine is found the admin is intimated. If the ip is not the one listed for the printers you would know that this is a new machine and SEP client needs to be deployed to this newly detected machine.