Seat for I/O engine cover ?

[BigLew]

I checked out your hyperlink.

If you're married to the idea of mounting it on your I/O cover, then all you should really need to worry about are the six holes you will be leaving in the engine hatch cover. They are easily filled in with epoxy and filler. Just make sure you use an adequate base plate inside the engine hatch in order to support the exerted forces of the pedestal. In addition to the Seat you cited on Ebay, you'll need some sort of spider and pedestal base.

The bean bags or directors chairs are your best bet in the interim. Go for it and good luck!