Can you more clearly define what a light installation is? What properties are you wishing to achieve and why? Are there limitations you are seeking to address? Or are you simply seeking a stationary chromebook, but with Qubes?
Here is an example use case: I have an install on a laptop with 4GB of RAM, which forces a lightweight installation due to resource constraints. Lightweight in my case means limiting RAM usage and accepting I will only be able to run a limited number of concurrent qubes.
Lightweight can mean different things:
Lightweight due to limited RAM or hard disk space
Lightweight to ease usage/maintenance by reducing unneeded clutter
Lightweight to compromise some security by accepting tradeoffs due to unique situations [stationary, always at home, etcetera]
For a Chromebook-like use case where all browsing activities are in a disposable qube, you might want only a persistent “vault” AppVM for any login credentials and a Fedora DVM template. Note that “vault” is just fancy for an AppVM that has no network, and has KeePassXC as an available application. Qubes gives you the ability to place your own meaning to a qube.
What’s important is for you to define what you are seeking, and make the installation match. You can perform a 100% standard install and only use one disposable qube at all times. The question is if you can already do that, what more are you seeking?
With lightweight I’m referring to low cpu-usage, sorry for not being clear about that. To be precise I would like to extent my battery life. Qubes OS gives me two hours while for example Fedora keeps going for at least 10. I know that’s due to the vm’s but I don’t know how I can reduce the impact they have on my battery life