Here's an alternative... Bass guys for years have been using something like a large comfortable bicycle seat on a pedestal for those that want to partially stand up while fishing but also need some support - so you might want to take a look in that direction... The best part is that it not only comes with a plate and socket that allows you to easily install or remove it (with no hardware sticking up after it's removed..) but I remember seeing them with a shock absorbing pedestal (the pole that the seat is mounted on is two piece with an internal spring, etc...). You'd have to verify with the manufacturer that their materials are suitable for a marine environment...
Can't say I've ever seen one on a flats skiff but they do look like they'd have a real application on any skiff where you're in the bow all day long....
Post up what you finally decide on - there will be more than a few here interested...