There is a loft room above but putting ply on top of the joists will impact the floor above. Also concerned the thread would rip out of the 3/4 ply now thinking about it.

Another thought would be to screw some 8 X 2 between the joists (could screw through joists and into 8x2) with the 8" horizontal. Could then maybe bolt something through that to spread the load via a washer or something ?

I guess I could also screw some battens to the joists and then screw 3/4 ply on top of the battens. Then bolt something through that?