Tempest,
Your wide ratchet straps are a good item to use but check the tension on them about ten minutes into the journey for movement.
I like to tie the bow to the trailer base, not the trolley so that if for any reason your boat and trolley become separated from the base you have that added security.
Try not to tow with a boom up cover,so much windage and if the wind gets under the cover it will rip it to shreds.
I have some time ago invested in a flat cover with shroud openings ect so as to trail with that on and still have a useable cover for the away meetings,ie just one cover!
I also open the bailers when trailing the boat so as to keep it drained!
Dont forget the spare wheel for the trailer and a good brace to undo the nuts!!!
I have and you can also buy a board that screws to the lighting board that will support the mast at the rear end. You screw rudder fitings to it and the whole thing just drops onto the boat.
I have a rope that goes from that board,through the fittings on the boat and back to a cleat on the board again for security.
C P 🙂