You might be interested in using Blink gateway images for your upgrade.
These images are used for upgrade in the same way as CPUSE images, except that they come pre-installed with the JHF and many of the binary components. The install time is faster, you don't need to separately download and install the JHF, and it saves you a reboot of the JHF installation.
They work really well and in the future we'll probably make these the default.
Note that you need to choose the correct flavor - in your case a gateway blink package. You can download them from the official JHF page.
Due to the "pre-installation" we need to prepare different packages for gateways / management / MDM.
You can import these in advance on the gateway, just like a CPUSE image. You can even run verify in advance to make sure there are no issues prior to the upgrade window.