It sounds like the government has stacked the deck hard against landlords.  

Removal of 3 layers of shingles and 1 of wood shake plus a new deck was another $4500.

The container roof would be use for the roof deck.

Don't bother considering ring shanks; just get some decent deck screws.

I can't tell you how many screwdrivers, hammers, wrenches, buckets, reels of plumbers tape, reels of electrical tape, saw blades, drills, flashlights, etc I have now because I left that one component back home.  

One, of course location, another amenities at the dock, fuel, dump station, condition of the ramps, depth of the water, what the docks are made of (decking of concrete or treaded lumber) covered, uncovered and the list goes on.

Most likely you are looking at a wooden deck and would need to have a cold process roof installed. 

Your maintenance should also be higher (the tremendous amounts of snow does a number on roofs and decks/porches), and if you pay the utilities/other expenses you should account for high energy bills during the cold months (typically October - April). 

The details and analysis in your investor deck presentation are critical.

However, I will allow them on the deck or on a post.