A couple of points for you to think about.
How big is your boat? The track to Kalumburu and further on to Honeymoon Bay is a very ordinary 4WD only track, and if you are towing a trailer boat that is big enough to head out to sea for 14 days, my thoughts are that your trailer and boat will be damaged by the time you get to HB.
Have a chat to the guys at the Mary Island Fishing Club in Derby. They have plenty of trailer boat experience in the west Kimberley coast.
Diving along the Kimberley Coast is not recommended. Crocs live around the off-shore islands such as Cassini Island. And they are much harder to spot offshore than they are up a creek or river.
Cheers, Ross