Pretty simple but all available vehicles as decoration objects,Including the cars from the lost world,Landed helicopters
Also ruined versions of ones such as the jurassic park tour car after it fell in the t rex paddock
These would go a long way to filling out some areas of the park. Despite them being "dead", it would make the parks look much more alive. I believe EVO had pulled off a parked vehicle in one of her videos as a decoration prop - somehow - and it worked really well.
I think they did that by either making the ranger station the jeeps belonged to inaccessible to them,Or had a wrecked vehicle and used the Invisible fence to move them
Also, the camping vans from the short film Battle at Big Rock would be great. Alongside camping utensils and a camp fire.
With those decorations we could replicate the short film in the game.