In general, plan to stop every hour or 90 minutes to check the whole load and the trailer for any issues. If travelling through the NYC or any other complex highway system, I would plan a stop before you get into the metro area and have to deal with all the interchanges, because it’s really hard to find a safe place to pull over.
Bring TWICE as much stuff as you think you need; ie old towels, duct tape, line, straps, etc etc
If your boat has bow and stern pulpits, that’s great because that is the easiest way to haul the mast, strapped down on the bow and stern pulpits. To prep the mast, remove the spreaders and jumper strut assembly. Mark port and starboard and put all that in your tow vehicle. Zip tie all the shrouds together, and then tie or tape the rigging to the mast in 3-4 foot intervals. The best way to support a mast for a long trip is to cut a 2×4, which will span the bow pulpit. Pad the 2×4, and the stern pulpit, with old towels or the like, duct taped. Strap the 2×4 across the bow pulpit. Then strap the mast to the 2×4 on the bow pulpit and to the stern pulpit. The excess rigging at the bottom of the mast will hang; what I do is lay it on deck near the bow cleat, and zip tie it to that. You can wrap and tape the turnbuckles with old towel or rag if you’re concerned about them scratching the deck.
If the boat doesn’t have a stern pulpit this becomes problematic because you either have to come up with something to support it at the stern, or you have to think about strapping the mast to the trailer, which is much less ideal.
For the boom: Don’t be tempted to throw it in the cabin. Strap the boom to the trailer down next to the keel. Wrap it in old towels and duct tape at the points where it rests on the trailer and strap it down super tight.
Buy the 10,000 lb ratchet straps. Don’t be tempted to get the cheap 3000 lb straps. You only need two. Check the attachment points on the trailer. There should be a pair somewhere forward, and somewhere towards the back of the trailer. The ideal scenario is where you have the boat strapped in a way that the forward strap can go across the deck, through, or in front of, the bow cleat, but then be angled slightly back on the trailer. Then, the rear strap, ideally, goes behind the winch bases across the cockpit, but then angles slightly forward at the trailer. When tensioned, they counter one another and lock the boat down onto the trailer. Bring tons of padding. Old towels work great. You need to pad the toerails, and the cockpit coamings and winch bases where the straps cross.
Also, here is a trucker “trick.” Don’t run the straps nice and straight and flat. They will vibrate and hum and drive you nuts, not to mention they will chafe. Each “section” of strap should have some twists in it. I do two twists vertically (from trailer to deck level), and one twist horizontally (across the deck).
You need to crank down hard on the straps because you do not want the boat to move!
Trailer and poppets:
In general, hopefully the boat is loaded well already. You need at least 10% tongue weight. I think mine rides around 700 lbs on the tongue, which is nice and smooth but doesn’t overwhelm my SUV either.
Hopefully the trailer is well maintained. Do all the usual checking of tires, brakes, pins, lights etc. Bring a grease gun to grease the hubs, etc etc.
Poppets: VERY IMPORTANT! Before you strap down the boat! Poppets hold the boat vertical, they don’t support the weight of the boat! They need to be snug enough that they support the boat without distorting the hull. The other thing about poppets when on the road is that they unwind themselves unless they have a lock bolt. If they have lock bolts, snug them all up so the boat doesn’t rock but that you’re not distorting the hull, and then torque down the lock bolts. If you don’t have lock bolts, then you need to somehow fix the poppet handles with duct tape or line. You will need to check these on every stop. I have had them unwind on me even when locked. Check them often.
Easy rule for gear when trailering: Soft stuff can stay in the boat, hard stuff should go in the vehicle. Everything inside the boat will bounce around and damage the interior so take as much crap as you can out of the boat, except stuff like cushions, lifejackets, sails, line and other soft stuff.
If in the well, that will ride fine. If on a bracket on the stern, remove it and stow it in the tow vehicle. The outboard bracket can’t handle the stress of a long tow and can break. Gas tank: Probably best not to transport a tank with gas a long distance.
Hatches! IMPORTANT! You have to make sure all the hatches are dogged down, latched, clipped, etc. They like to fly off on the highway and are costly and a hassle to replace or rebuild on these old boats. Dog the bow hatch, and even duct tape it if you are in doubt. Main cabin hatch; put the hatchboards in and the latch/hasp and lock it! Lazarette hatch(es), same as bow hatch, latch them, lock them, or tape them.
I hope this is helpful. Good luck!