Hello Mr.Joss,
Thanks for sharing your experience.
My setup is
Nauticam housing for A7RIII + Canon fisheye 8-15 + extension + 140mm fisheye dome port = 800 g
YS-D3 x2 = -50 g
Weefine 2300 focus light = 250 g
Total = 1000g + ~500g for 7 clamps and 2 arms
I think I will stick with only fisheye setup, I'm not a professional photographer and I'm not used to shoot macro shots.
I wish I will buy Nauticam diameter 70 x 250 mm carbon fiber floats x2 (buoyancy = 520 g each )
and weigh it underwater.
After that I will fine tune the buoyancy with high density foam or maybe buy small floats.