The portable version can be run from wherever it's located, it doesn't have to be "installed". So you could have an external drive with your content library and the portable Daz program and when you connect it up to a computer just use it from that drive.
It being 238mb might mean that it doesn't have any of the daz "essentials" installed because it probably doesn't have a runtime/content library. I could be wrong but that's what I would cut out to keep it as a small portable app.