I had a cradle built to these specifications and it is a neat fit. What I would say is that if you have it made in wood it is not inherently strong enough just held together by bolts through the corners. I have had some right angle brackets made up to strengthen the corners.
The other problem is floating the boat onto the cradle with the keel up without going too far forward. I have made up a rope attached to the leading corners of the cradle and looped over the bow roller to stop it in the right position. If you want photos of the cradle in use I can take some.
Kate