Quote Originally Posted by CRallo View Post
one failure point sucks.

a spear sucks.

sucks is a very technical term, btw.

I would skip the spear, build a plate like that and use the traditional bolts and washers to attach the weight to it.
I was thinking more of your seat bracket plate design like you have done. Just add a thicker plate instead of the scary spear...

You can add additional plates with longer bolts in 4 points, remaining flat with no spear and still removable like a seat.