I've been looking to do the same thing. put some sealant in between the spoiler and the hatch, then fiberglass/bondo the whole thing and blend it into the hatch making it a one-piece setup.
We've got a ton of snow up here. Its melting right now I hope for good. I hate driving in snow, but it can be really fun. I don't live in a very big town, so at like midnight theres nobody on our main street so my friend an i just go sliding around corners. Did a 360 and peeled out in the middle of the street and when i looked across the median there were 2 cops, kinda scared the crap outa me. lol