[htn123]

Great job Phedge,
One observation, with the original config, the bottom of the seat sits on the big brackets, pretty big surface area to support the seat.
Now when you put the spacer in, the whole seat will be support only by the bolts and the spacers..... pretty small surface area to support the whole seat.
How about a shorter plastic spacers and then a couple of big round washers right against the bottom of the seat so the seat has a bigger support surface area?
Just a thought. Hate to be bouncing on it for a while and the whole seat will fall down on those two bolts.