I picked my cradle up last night and you are right, the bolts are too short to use with the lock washer, washer, and lock nut provided.
In my mind, the bolt should start through the side the welded nut is on which is the nonmotor side on mine, which I bought the same splitter as you over Thanksgiving holiday. That way the cradle, which I thought should be on the engine side to keep splits from banging against the engine, can rest on the bolts allowing you to put the washers and lock nut on. I'll probably go and buy some bolts(8.8 M) that are about 1/2" longer.