Is there a stable post base for mounting fence posts on the deck?

[martinradbo]

I am going to build a 30 m² extension with a terrace/deck on the roof with a wood-based railing.

The terrace will be in the form of wedge-shaped joists (due to the roof's pitch) and regular decking boards 28 x 120.

The problem is figuring out the attachment of the posts for the railing. At the edge where the joists are largest, it might be possible to attach posts with screws into the joists (45x220). But the thinner the wedge gets, the worse it is. Already when the joist is 100 mm high, it's insufficient. A fence/railing 110 cm in height should withstand a person weighing 80 kg "throwing themselves" against it without giving way.

Steel fences often have a post base that is screwed onto the decking. Therefore, I am looking for similar post shoes like this one:

but for 70x70 or 90x90 posts.

Preferably, the manufacturer should guarantee that it holds.
One example is this:
https://www.hornbach.se/p/markfaste-kaiserthal-71x150x100x60mm-rostfritt-stal/7128610/
where you can see in the datasheet available here: https://media.hornbach.se/hb/datasheet/as.80179845.pdf
what the product is rated for. Maybe it is sufficient for my needs?

Instinctively, I would have wanted a larger plate at the bottom with more screw holes for better stability.

How would you do it?

 

[Demmpa]

Horizontal joists across (possibly diagonally) under the decking that the post base is screwed into with through bolts.

 

[martinradbo]

Horizontal beams across (possibly diagonally) under the deck that the post shoe is screwed into with through-going carriage bolts.

Yes, reinforcing underneath is a given and not a problem for me. Whether it will be carriage bolts or strong wood screws, we'll see. But regardless, there will be less to play with the closer I get to the old house. That is, the wedge-shaped beams are calculated to be as little as 30 mm high at the thin end. At the innermost part, however, you can screw the posts into the wall, so it will be completely stable there, but a meter further out, there will be perhaps a 40-50 mm beam + deck, so it would take a lot for it not to hold, I think...