Depending on the grade of the 1/8" you might be OK if you use backer plates where you bolt through. I'd also be worried about the weld points as well.
Really 1/4" or 3/8" would be much better.
Depending on where you live I can point you in the direction for some flat stock.
"The Chesapeake does not impress those who know it best as the grandest or most of anything. For all its size and gross statistics, it is an intimate place where land and water intertwine in infinite varities of mood and pattern."
William W. Warner "Beautiful Swimmers"