Safely add Electricity to Seasonal dock for 110V boat lift?

Since you guys know everything.... 

I'm a lake and boat rookie, but last fall we bought a house on a lake, and just bought a ski boat.  Hooray! 

So, next piece of the puzzle... a friend of mine has a 110V boat lift that's correctly sized for my boat (2000 Correct Craft Pro Air Nautique), but my concern is how do I "plug" this in the right way?  My first call is to an electrician to quote getting a GFCI outdoor outlet trenched down near the lake, but that doesn't help me get power down a seasonal aluminum dock in Michigan to actually  plug into the boat lift motor.  There's surprisingly little info that I found via Google, yet I know there's a ton of 110V boat lifts out there.  

For what it's worth this is a cable vertifical lift hoist, and is going in an inland lake in Michigan.  I have a 40' dock already so it'll plop down next to that.  

So is there just like a marine grade extension cord to go from GFCI shore outlet to the boat lift motor?  Some kind of temporary permanent flexible conduit along the dock itself that I'd take out seasonally?  

I see they also make DC motor kits with solar chargers, then you just add a couple batteries and boxes to the mix, but that's a minimum $1,500+ additional, and at that point it seems I'm a good ways towards paying an electrician to get an outlet nearby which would likely come in handy for other things.  To be determined I suppose.  

I don't have any first hand experience with this but I'd start with the lift manufacture.  I'd also take a look at the ABYC shore power recommendations since what you're doing (plugging a 110VAC device that sits in the water) is fundamentally the same as a shore power hookup.

Having an electrician get proper power down to the dock is the first step.  It'll depend a bit on how big the lift/hoist is and the power it draws.

IMHO, run more power or cable down there than you think you'll need.  Much of the cost is in the labor more so than materials.   Consider installing a proper marine grade receptacle to provide power to a boat that can use it, even if the current one does not. You can get adapters to use it for other things and the plugs will be rain-tight. It'll be much easier/cheaper to install it now than to go with the bear minimum and add it later.