The biggest problem around here about having a roadside garden is that people have a tendency to raid it. It is a private road but other people other than your neighbors may go past it. Most of the community garden plots here especially those that are not fenced off from the public are raided all of the time. Even the fenced ones are regularly broken into when people know where they are and can see the fruit. The homeless even regularly go into some of the community gardens at night to sleep because they feel safer and they use the garden water to bathe and eat out of the gardens.
How is the soil there. A good garden site needs to have at least 6 hours of sun, be close to a water source, and have a well amended soil.
Happy gardening in Hawaii. Gardens are where people grow.