My suggestion is to look at a development life-cycle that I've seen used in some "Waterfall Release" companies using agile.
The key to this is the word "Potentially" as in "potentially releasable Increment of “Done” product at the end of each Sprint.". Scrum doesn't actually say to ship every sprint. It just says it should be releasable. This has been widely interpreted as being "Ship every sprint" over the years. This in turn leads to many Enterprise companies only using Scrum/agile in the strict limits of the "coding" phase and then wrap waterfall around this.
Instead you need to separate the concept of Deployed and Released from one another. You need to step down the path of Continuous Integration.
- Deployed: The feature is done, it is in the system. It is just under a flag so that only specific users can see this. Sometimes referred to as A/B testing. You start by deploying the feature internally and testing it yourself. Microsoft's TFS team does just this every three weeks with it's cloud service. Internally they see the feature a week before the public does.
- Released The feature has been released to one or more users by changing the permission flags on the feature.
You build everything in your sprints to be deployed, even if that deployment is an internal production mirror. When you have enough features to warrant a release to the public, you just flip the switch and make them live. You separate the act of building from the act of giving it to the customer. Not unlike manufacturing where you could have a thousand Wigets in your factory before you ever sell one to a customer.
The other advantage of this method is it means if you have to, you can ship any time you need. For example, imagine a major security threat comes along. If you are able to ship every two weeks and just choose not to, then if there is a major security issue, you can choose to release.
This technique is being used successfully by most of the major "service" related internet companies now, Facebook, Google, Amazon, Apple OS, Microsoft Cloud anything, etc.
Move your development away from Waterfall, keep your product releases to the customer on their longer cadences.