Just learned this game over the weekend. It seems like a lot of the unwritten-rules tension comes from the fact that the start word is public. So one decent strategy can be to do [start word] [article/conjunction] [synonym for destination word loosely related to start word but still arguably within the guidelines]. Appears that a secret start word would mitigate that. And I don't quite see the reasoning for even having the start word public, so wanted to check with BGG before implementing.
If you hide the start word that is fine for the first word of the turn, but as soon as someone guesses the first Destination word correctly, that word becomes the new Start word, and there's no hiding that - everyone knows what it is!
As for your clue ("bridge with raft" as Jay applied it), that's fine as long as it's a coherent thought.