This is one area that I really enjoy... (Sled and Flo-Form Fan)..
What I do is use a large lifter kite (Look at my Photo album in Bio if you wish) depending on the wind.. But what we prefer 24 or 36 Sleds on days where winds are between 8-20 mph. I always go overboard on line when hanging laundry also. 250lb for the 24 Sled and 500 lb for the 36 Sled.
My preferred method is carabiner vs. line loops.
I attach line laundry with a carabiner and wrap the main sled line at minimum three times around the carabiner . I equally space my laundry (using arm lengths to measure) with the laundry with most drag towards the anchor side. You may have to adjust the amount of laundry depending on winds and what the pilot kite can hold steady.
On the laundry side, I use sturdier/bigger/heavier gauge carabiner (Aluminum for light weight) for heavier laundry and smaller for lighter laundry.