On the weight I used a 3 seater couch 06 Stx15 kawi 900 pounds, it was late and it's the only couch weight I know so I used that for my example, my bad. The blaster must be way lighter though
On the washer I was trying to keep it clean & simple, two would be stronger for sure
It's been awhile since I carpeted bunks, when I did it I copied how Zeiman did it, I removed the carpet and used it as a pattern. They had the seam on the bottom of the bunk with the staples on the bottom, which made sense to me since the ski would be sliding across the top of the bunk opposite the staples.
One thing I thought would be trick but I never tried it is to knock the corners off the 2x4. Cut 45 deg angles of the top of each bunk length wise, "just cutting the corners off" not much more to make it more roundish. The carpet wears more on these corners I noticed. On my stand ups where it sits on the bunks the hull is curved upwards but the 2x4 is flat so the hull rest some on the corners of the 2x4