Aww no fun. I hate it when you've seeded and watched so long for those crazy flowers to bloom and then poof!
Seriously, any chance of putting up even a 2 string barbed wire fence using tposts. You can engineer it where there is a section that the Ruitans can open up for their parking use, and then put the barbed wire back, not too difficult.
A relatively inexpensive quick fix until you can afford a more permanent solution. Then again you might be suprised how much that tiny barbed wire fence keeps people out. Maybe plant some paulonia trees along the edge or something. Sometimes you can find inexpensive pine saplings or something quick growing like that.
Good luck!