After I got the blocks under the transom, I jacked up the front of the trailer/boat with a large floor jack. This made the transom set down on the blocks and raised the front of the boat off the trailer. I then block up the front of the boat and removed the jack. Rolled the trailer as far as it would go until the first cross piece hit the front blocks. Put the jack behing the cross piece, jacked up the front of the boat to move the front blocks out of the way, rolled the trailer forward until the next cross piece hit the jack, block it up again behind the next cross, etc... repeat as necessary.
Here we are halfway through the process.
2003 Prostar 197 35th Anniversary
1990 Prostar 190