Thanks guys!
Yeah - It was not as smooth as I would have liked. Mainly because the old trailer was screwed and the rollers were shot! You have to be careful as you move forward and it drops off each roller. A trolly jack was used to to take the weight, and then lower it down onto the next roller that was actually too low. Slow and stead, and easy done.
I have the weight distributed pretty evenly. We rolled it up onto the wobbles and the adjusted all the other rollers around them, as the boat was sitting nicely above the guards, at what looks to be the right height!
I used a trolly jack under each of the keel rollers to lift and put weight on them one at a time. I also lowered the nose roller so that the boat looks to be sitting level on the trailer when winched all the way up. A trolly jack is a must for adjusting the rollers, so you can really put some weight on them. The rear is about 100mm or so in from the arse.
We had to grind some bits off as they got in the way, but the old trailer is screwed anyway. So it' didn't matter.
I must mention - At no time did the boat feel or act like it was going to fall off the trailer. It was supported by the wobbles from the get go, so no chance of that.