Some over the counter nausea tablets contain scopolamine, which is one of the active ingredients in Datura. It is sometimes listed on the box as Hyoscine Hydrobromide (another name for scopolamine), so tablets of this kind may help you.
The ones I have contain 300 micrograms of scopolamine per tablet, and it recommends to only take 1 at a time. I once took 2 before going to sleep, and although it only had a minor effect, it was very strange, difficult to describe. As I understand it (please do correct me if I'm wrong), 1 milligram of scopolamine is generally a fully psychedelic/delirious dose, so I'm not sure I'd ever chance taking 3 of these tablets in one go.
If you want to do Datura for nausea, I personally think the tablets would be a better idea, as you can be sure of the exact dose you're taking, whereas everything I've heard about Datura suggests the concentration levels of the actives can vary wildly and unpredictably between plants, which to me is a risk NOT worth taking.