John, if I read your posts correctly, it sounds like the boat was not strapped down to the actual trailer. I can't believe they relied just on the tension in the winching strop. if they omitted to tie her down to the trailer, at least one for'd and aft tie on each side to the side pad support struts, then the carrier is liable with a capital L in my view.
Actually, back in my trailer boat days, if I was trailing one of my trailer yachts any distance, (towing it myself) I would do that, as well as making sure the winch was tensioned - and a secure extra tie added between tow hook and the main winch support as well. This completely removed any chance of the boat bouncing around. Never had so much as a scratch as a result.
On a more positive note, re the mast raising. After I partly dislocated my right shoulder trying to do that just by brute strength - yeah stupid is as stupid does - I decided there had to be a better way. Because it was a masthead rig, the mast on our first 20' boat actually weighed more than the mast on our 26' second boat.
What I did was use the spinnaker pole, (but if there is no such thing in your rig, any suitable alloy pole with appropriate end fittings would do), attached to the front of the mast. The spinnaker mount if there is one is ideal, otherwise drill and fit something like it. Then use a short brace line from the outer end of the pole to some secure place each side rail, opposite the base of the mast, to hold the pole in the midline, then by attaching the forestay through the end fitting of the pole, to some suitable extension line, one can then run that round the anchor roller (or suitable block if no anchor roller), and lead that back to a sheet winch on one side to use to wind the whole thing up. With just a modest lift of the mast to say one of the supports you have fashioned, to start the lift, it would then be possible for someone to begin winching while you guide the mast as it rises. The rest then is easy. I hope you can visualise what I have described. Best of luck.
PS, now I have looked right back to see a picture of your new boat, I realise the mast base is very forward, so you could adapt the suggestion above by taking the forestay extension line forward of the boat & trailer, to say a fitting on the towbar of your vehicle, to give the right sort of leverage. But actually, re-looking at the photo, it does not look like the mast is all that heavy, so probably your mast rest system should work, but if not the system I described above should still make it a lot easier to raise. However, as I now see there are no sheet winches, just another person, or yourself, pulling on this rope would raise the mast, then you could cleat it off on that aft cleat while you secured the forestay.