Looking good, Bruce.
3 months after finishing my SMB beds, I found the perfect free bed container - empty cattle "range tubs". These come filled with 200 lbs of the 37% protein + minerals stuff for cows that I had previously only seen in 40 lbs blocks. The empty plastic tubs are about 32" wide and 24" high - I figure one could cut them in havlf, height-wise, and make 2 SMB beds out of them. After this Winter, I have 7 of them (I think) waiting on a SMB pond in need.
Maybe you can find someone feeding them to cattle around you before you try out SMB spawning in the future.