It's mainly a worry when closing the ct Kim. Everything bolted to the hardfloor gets lifted by the winch and strap. If the floor is too heavy the strap bends the tents bows, especially the centre one, when you wind the floor up off the ground.
We have at least 40kgs in 2 boxes that travel on top of the ct once it has been closed. No probs with the aluminium bracing on the floor holding that so far and we've done many a rough track/road.
To lighten the floor I will be removing our second pole carrier when we get home. The weight of that, plus the old fishing rods in it, is too much due to it being opposite end to the floor pivot point.