Matt do NOT use steel wool. Use brass wool or bronze wool only the steel wood shardes will in bed in the wood and rust.
In the past I tried the finer sand paper and all I did was make the platform VERY slick when wet. I used 80 grit paper and brass wool to open the pores so I could get all of the dead sh8t out. The Teakgaurd stuff came with the wool and a brush and the cleaner and the finishing coat. I was really impress how a lot of elbow grease and sanding work. The Teakguard still looks like to last pic and thats after the last half of the summer and us sliding off the back with the boards on.