Re: Parking a boat on an inclined driveway
The wheel clamp looks interesting. Another option might be one of those wheel stops, or wheel guides that you drive on to help people line up in their garages. I have seen aluminum ones before. Here is an example of a plastic one.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94079
I don't know if it would work for you to back into, maybe open the garage door and back in part way then put 2 in front of the tires and pull forward to the big stop? They might work great for parking on hill in the street as nobody could remove it without physically moving the boat.
Your driveway does not look too steep but my jack wouldn't raise high enough, but you would have to do some serious blocking to get the bow elevated. If you don't want to move that much wood every time maybe you could take one big block (maybe a chunk of railroad tie) that you could move easily and cut the bottom to match the angle of the driveway so the top would sit level to elevate the jack a bit. You could mount one of those trailer jack wheel stops (like Part # 50080555 here at iboats) on it for piece of mind.
I would seriously consider paying to store it though, if it were my house and space were that tight.