Wide plank red/white oak flooring fasteners

[Naison]

Hello all. 

Looking for some advice on fastening 2x8 and 2x10 red/white oak floor boards onto a 16"OC joist system. (there are 4 main 10x12" carrying beams that span 32' spaced 12'OC with 2x10 red oak joists mortised into them 16"OC, entire deck is 32x36') 

My original thought was 3" GRKs from underneath, either 2 or 3 screws per joist but a friend says they will pull out when the floor shrinks. A previous barn I did in wide plank pine (mixed 7 to 14" wide) used GRKs countersunk for plugs, nothing has seemed to move or pull in a year but not much time has passed so maybe not a good comparison.

I could go to something more substantial like 4" 5/16 GRKs countersunk from the top but that is going to be a lot of money for the size of the deck. 

I have read some previous posts on cut nails but worried about staining and their holding strength. 

Thoughts concerns?

[Revival Sawmill]

Could you peg them down?

[scsmith42]

Are the floor boards fully dry?

[ScottCC]

Use pole barn nails through the face but grind the head of the nail square.  Then send out to be hot dipped galvanized.