In regards to being able to deal with potential for salt buildup " It appeared possible that duckweed removed up to 9kg salt/ha/d when grown under fairly optimal conditions, suggesting a potential for duckweed to rehabilitate saline land and water." - Duckweed
I'd think some sort of water wicking bed, with an overflow area where duckweed could fill a shallow "pond" type of area and then be dispersed as a surface mulch, composted, fed to ducks / fish. Using urine in the garden, even diluted, tends to build up a certain odor. Note, one tends to be more sensitive to the pee of others so your backyard may smell fine to you...not so much for others. A wicking bed, with clay or pond plastic base, ag-pipe, scoria / rock, and a pipe with a good fitting cap would really help to keep any potential stink in.
Not particularly related but a scary species of tree you'd want to avoid - Tamarix aphylla "Athel Pine"
"consume large amounts of water - up to
twice that of Willows (Salix spp.) reduces water availability for stock and the
environment, alters the course of rivers and increases sedimentation rates. It
concentrates salt, which is excreted by its leaves, making the ground around Athel
pines more salty
and excludes native pasture grasses and other salt-sensitive
plants, thus reducing biodiversity. It can also cause corrosion of gutters, metal
buildings, bores and equipment when planted adjacent to infrastructure, and falling
limbs are a hazard to humans and stock." Truly a horrible tree...