the advantage of the cad plate is it's cheaper and will prolly last as long as the parts being bolted together - advantage of the ss is someone gets to make a good livin off ya and you feel cool at the car shows [you've already seen the disadvantages!]
figure all the bolt sizes and go to a hardware store for a set in galvanized - bought by the piece prolly be about 20$ and will be reuseable when you replace the wood 20 years down the road
Bill