Tidalist, congratulations on your new Adventure and welcome to the forum. Foam blocks are better than nothing, but either flipping the boat upside down or using proper saddles would probably make the boat ride better.
The Drivewell is a strong point on the boat if it is riding on its bottom, so this should be over the cross bar if proper balance permits. Although it takes a little longer, I use two ropes at the well, one anchoring at each side of the rack. This positively secures your boat to the rack and you don't have to cinch it so tight and risk denting it. Even if it slides around a little, it won't go very far!
For the rear tie-down, again I find rope more adaptable than straps, and loop around the boat once so it doesn't want to slide-to-side.
There are many other ways to accomplish the safe transport of your boat however -- as long as it doesn't fall off or get crushed!