[john walker's workshop]

I'm obviously not a carpenter, but I'm sure I can pull it off with a little layout help.
Going to pull the old wood decking and install Trex composite. From the outer edges of the end joists it measures 23' 10" across. The width is 12' 10". Boards will be lengthwise. 16" joist spacing. The Trex is 20'. Where the board butt, I'll double up the joists so one clip per joist. Trying to figure out a butt pattern that is professional looking and keep waste to a minimum. Is there an online planner where you put in the dimensions and voila, or is it obvious to a pro. TIA.