As metnioned in the previous post, yes, cnMaestro can be used to manage ePMP devices and that includes performing bulk software upgrade of devices.
Can you clarify the problem you are experiencing? Have you been able to successfully onboard an ePMP AP and SM? If so, then they should appear in the device tree when you click on the MONITOR - DASHBOARD menu item.
Assuming you see the AP and SM in the device tree, you should be able to click on the device in the tree and see information about the device on the dashboard (to the right).
To perform a bulk software upgrade, use the main menue to select OPERATE --> SOFTWARE UPDATE. In the tree, click on the on a parent folder (such as System or Network folders). Using the pull-down menu, select the "Device Type" to be "ePMP (Sectors)". Select the software image that you would like to apply to the devices. In the table below, click on the checkboxes to select the devices that you would like to upgrade and then at the bottom of the page click on "Add Software Job". In the next tab, "Active Jobs", click on the "Start Job" button.
You can leverage DHCP Options 43/15 to configure cnMaestro On-Premises URL on SM devices as long as they are getting IP address from DHCP Server configured/managed by you.
Please refer to section - DHCP Options (Linux) in User Guide to get detailed steps about the same.
I am assuming that in this case you don't have control over DHCP Server, which is providing IP address to all the CPEs. If this is true, then you cannot really leverage DHCP Options 43/15, so you will have to set cnMaestro On-Premises URL on each SM device.