Lack of structure in a no-knead pizza I hope this question is not too vague but let me try anyway. I followed a NK recipe for a pizza with the following baker's percentages

100% flour with 13% protein and W300/320 according to the manufacturer's website

75% water

0.2% dry yeast

2% salt

then some SF folds, 1hr at room temp, then 18h fridge and the last 4.5h again at room temp. The volume did increase compared to the day before, not too much but enough to make me decide to go forth and not tossing everything.

When I tried to stretch it on a surface dusted with semolina flour (see below), the structure seemed quite loose and, although I could move it from the working surface to the baking dish, I obtained some thin spots and a "mattress" effect in other points.

If this were a kneaded dough, one could say that the lack of structure is due to lack of mechanical work, but what can be said in the NK case?

Perhaps this flour couldn't make the whole water in a NK recipe, although I find online stories of people who make 80% hydration with it with no problem.

During the mixing,  I noticed was that the first 80% of the water could be mixed all right and when I finally added the remaining, the dough started to become suspiciously wet. But also I thought: it's a NK, it is supposed to be wet, right?

Moreover I wonder about the stretching technique itself. Many "roman style pan pizza" are about 80% hydration and are stretched out on a board dusted with semolina flour, then flipped to lose the excess flour and then moved to the sheet. It is exactly during this flip that I noticed how loose my dough was. 
This technique is used for kneaded doughs, though. 

In other NK recipe I execute, the dough is stretched directly on the baking sheet greased with oil. On one hand, in this way I have no clue how loose my gluten structure is, on the other, I don't make a mess and I can obtain a uniformly stretched pizza/focaccia. Comparing these techniques, does it make sense to say that the former is more indicated for kneaded doughs and the latter for NK?
To create gluten from glutenins and gliadins mechanical work is required. So if you want to stick with the NK approach, switching to an even stronger type of flour (Manitoba) or special purpose flour (e.g. Mulino Caputo Nuvola Super) might be your only option. But even then chances are high that the results will not be as good as they could be.