At my cabin there is an enclosed porch with a shed roof. There are currently two sliding glass storm windows about 6 ft wide by 3 1/2 ft tall. I want to replace these with three new Pella sliders about 4 ft wide by 4 ft tall. The present header is a log about 4 in diameter with posts at each end and in the center. Then, each window is framed inside 2x6s but not a traditional framed header. I'd like to leave the log header and install three windows with two posts using 2x6s for the load bearing wall and frame for the windows under the log header. I don't want to add an additional double 2x6 header over each window because that will take too much of the available height, lowering the window too much. The present architecture has been there for 40 years without incident. How important is the standard building method in this situation?