Just a thought, but depending on what you end up liking downhill, you may get to the point where you don't like the skate trucks. If you just want to do freestyle then ok, but if you want to freeride, faster runs, boardercross etc. you're almost certainly going to want channels. If you went the trampa route, which is a good idea, the deck would be specific to skate trucks.
May be worth borrowing a board with channels for some down hill runs if you haven't already.