Hi Marc,
I have been working on a development environment for the oVirt. The environment is basically two VMs running beside together. One runs the engine, second is a host that runs the vdsm with nested virtualization.
I am now working on the vagrant file with orchestration to make the environment setup easier. So if You would wait for a few more days, You will be able to start from my setup.
As for the containers. For you to have a full test setup, you would need to place a VM inside the container and run a nested virtualization inside. This is what the two projects you mentioned are doing. Therefore they are not that lightweight as you would like.
I would recommend using the VM environment, which is the simplest solution.
I will send a reply again once my environment is up.
Petr