Yes Jack plaes are nice!! And that would work well with your wellcraft Carl.
His transom the way it is will not take a 25" shaft!! Way to low.
Carl with the motor on the boat and in the up position grabe the lower leg and lift up and down to see if there is movement. the again side to side. You should be able to bounce the boat around the trailer with out moveing the transom walls.
Another way is to drill a couple small holes on the inside of the transom 1/4, and see if you get dirt or clean wood. Just remember to fill the holes back up with 5200 or marine tex.
I belive you are the guy who sent me a email?? But if not I am a member of a site that we all own the same boat and have made all kinds of repairs to the same boat.
http://wellcraftv20.com/ Just click Gallery to see diferent peoples boats or forum to get to a message board like her. It free tosign up!
Hope to see you there!! I will always answer what ever questions here also.