baaa haaa haaa ....

sorry to laugh at your plight bud.......but that was funny.
thanks for showing the curve to the transom.....that is what i needed to see.
ok......you want my 2 cents worth?
many many of boat has been built with a small transom....
single piece transom about 26- 30 inches wide....for the key hole only. Tab it to the stringers......and glass the rest. bang...done.
the key hole, as you know, must be flat....there is no playing with that....it must be flat or your boat will sink. so that area will have to be pulled to the glass....but if you go just a foot around the keyhole ....that is enough. when you glass the round hole from the out side.. that will give you your flatness and parelellism from the out side.
if you wish.....then you can add the 1/2 inch ply in layers to the rest of the curve......but 4 layers of 1708 over the existing curvature outside of the small transom is just fine. no wood necessary
that will solve every problem you are facing.......geez bud...i wish i was there to help....we would have that done in no time.
since you are not taking the cap off......the cradles will be fine. to firm it up so it does not wobble when you are walking around in it......you can just put some 2x4's form the garage floor to the under side of the chine in the front and then possibly one set aft...... it will firm it up so it wont move.
cheers
oops