You have several solutions:
you can create for him/her a very simple mashup using single configuration. Basically each single sheet/chart has a unique url. The sheet url do not expose your customer's nightmare tab. So you can simply expose the single sheets and create a simpe navigation between them
Our Qlik Community members have provided you with a variety of useful options, the best one to use is the single configurator, mentioned by Vincenzo - which is available from the Developer Hub interface. You may want to take a look at this video to learn more:
The Single Configurator will take an existing app and allow you to create a URL for it that you can link to from a page or provide standalone.
Let us know how you do, see screen shots below:
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