Every other question seems like "Thibs I train with my dog, can i have him lay on his side and I use him as a sled?" facepalm
I, like you and jj77 have ironically all thought about saying this exact same thing. I Did post in the livespill a few days ago, as I was asking these same ?'s, and eventually ended just making the damn sled, cheap and easy. And I love the f*(Ing thing to be honest.
...but yeah...people please stop posting about this and simply follow advice/instructions of posters here or look for more specific directions on google or something...its worth the time and investment.
I literally spent 3X the amount of energy and time thinking of and trying out potential eccentric-less exercises compared to the time it took to actual build the damn sled itself.