I bet it will be just fine. This plant is tough as nails. I think it would take gasoline and a flamethrower to kill off my SAC at this point. They do seed around the garden but I wouldn't say it's invasive. A lot easier to pull those seedlings than the Blackeyed Susans I used to have. :) Just out of curiosity, do you have anything to help the vines climb the wood to your deck? The wood seems kind of thick around and the vines will need something smaller they can grab onto for support. Believe me, once established they will be monstrous. Your shrub that's 5' away will be swallowed if you don't take measures. I thought it would be nice to train one of my SAC along the top of our 4' fence. It definitely is pretty when it blooms, however it engulfs the 2 Viburnums on the other side of the fence, as well as the Thujas that are about 8' down the fence-line, tries to climb our fastigiate Norway Spruce and generally tries to eat anything within 20' of its path. I chopped it mercilessly this Spring and it's still going strong. Beautiful plant but needs a firm hand to keep it in check or else lots and lots of room to roam.

:)

You do not need to cover the roots with rocks. What is meant by keeping the roots cool is keeping them moist. Rocks may actually hold heat from the sun and warm the root zone. Mulch is a better idea.

SAC is such a monster that you don't need to take any special measures or do any babying.

I am in Zone 5 and get no seedlings, my plant is about five years old, I hard prune at the end of winter and do some more pruning throughout the growing season. This baby will take over everything in its path.