This is just a hypothosis, but when it comes to reproduction in the sauropod dinosaurs, could it be possible that the males would be smaller in terms of weight compared to the females?

Because sauropods are the biggest animals on land, and if the male was the same size or larger than the female (like in elephants) and if he mounted her, the weight may have been too much for the female to bare.

I've even heard somewhere on a documentary that Ken Carpenter calculated that the bone strength in dinosaurs wouldn't have hold if they mated the elephant way.

But if the males were smaller, in my opinion, would have been just enough to allow successful breeding.

Again, it's only a hypothosis, but could this be a possible solution?

What you propose is possible -- we see it in some other animals, for example in the many spider species where males are much smaller than females -- but I know of no evidence for it. But in this case, lack of evidence doesn't tell us much anyway -- we have so few well-sampled sauropod species that almost nothing can be said about how populations varied.

I think you must have misread whatever it was what Ken said: bone strength would not be the limiting factor, and he would know that. Muscle and cartilage both become issues before bone.