G'day Rod Out back,
I've no experience with the gums, but
maybe you could experiment with some of the species that thrive in low lying
coastal areas. It would be interesting to see how sheoaks, paperbarks or
even figs might go. I've seen gums in brackish spots, but I don't know what
type they were. Maybe National Parks or Forestry dept. would be a good place
to ask. The large growing paperbark (melaluca qinequinervia - (( don't trust
the spelling, and there may have been a name change)) is a beauytiful
spreading tree, and casurina glauca is quick and handsome. If seen them both
growing very well in high tide inundated swamps, right down to the
mangroves. I've also noticed tomatoes naturalised at the edge of such
swamps, free from their usual pests. Any way, it would be interesting try
different things, so good luck.

China
Wingham
NSW