Hey John.
I have the same-ish trailer. I will tie a trucker hitch on that mast rest in plane with the bow to keep the boat in place as I pull out. I like your idea of adding a dedicated attachment point with a U-bolt.
Would love to hear other people's thoughts but I always retract that bow rest. I’ve had it beat up my bow. I would love to replace it with something more custom-fit. Then, i’d be more comfortable using it as a positive stop for spacing the boat on the trailer. For now, I don't use the bow rest on my trailer. it’s a little bit of a calculated guess lining up the boat on the trailer. I look at how the bulkhead lines up with the trailer axles and try to center the weight between the axles. This last fall I had to dip the boat back in the water to slide it forward on the trailer.
For launch at our location we need a 20ft(or more) tongue extension. The grade into the water is very shallow. I borrow my clubs extension which is different sized sections of square tubing slotted together with large clevis pins. Attached is a slightly older version of the extension. This whole extension can be made with a kit from northern tool, square tubing, and a bit of welding for the wheel assembly.
To accommodate this extension, I had a section of 3x3 square tube welded onto my trailer just below and behind the tongue. You can just make it out in an attached image. The extension slots into the open section of tubing and is held in place with a large clevis pin.
Lastly, I’m attaching some video of the club pulling another Ensign out with said trailer extension.
-Bryce