Too Much Weight?

[Jaws]

So I've already got a 180G tank with about 30G of water in the sump on the third floor of a new condo building. The tank is set up so the weight is spread out running perpendicular to the floor joists plus it is located against a retaining wall that divides my suite with my neighbours suite. The contractor and myself came up with the placement together to ensure the floor would hold it. The window on the outside of the building is perpendicular to the wall between me and my neighbour. In the corner in between the window wall and the wall between me and my neighbour there is about 4 to 5 feet of space which I would like to fill with a stand to hold a few different levels of tanks. One for a denitrification bucket, one for a topoff, and one for a refugium. The total weight should be just under 1000lbs. The total weight of my 180G tank is about 3000lbs so this would total about 4000lbs over about a 16 foot area of floor joists on a retaining wall, plus the new stand will be pushed into the corner of the retaining wall and the outside wall. I hope this all makes sense.

Can anyone comment on whether or not they feel this will be ok or not and why?