Where do most people use tie down straps (and what size for a 5,000lb boat (Parker 23SE) - across the gunnel or at the transom? I've read some info about bow chains and turnbuckles/ bolts for added prevention. They would help the boat from moving forward if there is an emergency stop. How are they connected to the trailer? In general, what are the best safe trailering options to secure the boat? Any pics would be helpful.