Since the economy tanked in 2008, Dan Naor’s Harborview marina has had at least 1.6 acres worth of unused space, and he’d like to turn it into a jumbo-size version of the handful of floating “wetlands” that currently bob in the harbor, planting rosemallow, sea lavendar, and salt grass to improve the scenery and clean the water. Naor’s plan would also include platforms to allow up-close appreciation of the man-made marsh.