I fancy getting one of those childrens' bath toys. The ones that attach to the side of the bath, and have a funnel at the top and things that spin and move when water flows through them. It would be a test of aim as well as flow rate.
https://dummy-magazin.de/
The front cover of the current issue (81) of Dummy magazine in Germany seems to illustrate German attitudes to rural urination. Alas I don't know enough German to understand why she adorns the cover.