80mm deck screws long enough for joists???

[Sculdugery]

Hi, would i get away with using 4.5 x 80mm deck srews for putting the frame together? 3 No. skewed and joist is 6x2

Would this size screw also do for the support legs? ill be using off cuts from the joists and 3 screws?

Thanks

 

[big-all]

way to short minimum 90 for 2 50s face to face 110mm when connecting 50 mm into end grain or bigger timber

80s are ok for 35mm onto other timbers 2.25 to 2.5 times the timber size is ideal ratio but minimum 2 times is advisable