What nails for double boarding hit and miss fencing

[tripledots29]

Hi all,
I have a pre-existing fence on hit and miss style. The boards are 16mm thick and the struts are 32mm thick. So a total thickness of 48mm/1.8inches.
I was just wondering what nails I should use to fit the new boards in a hit and miss style for privacy. Our neighbours have already done this on their side (not very well, picture attached). I can't really justify a first fix nail gun just for this job but we do have 130 panels to do so a nail gun might be a help. But will a second fix gun suffice with these thicknesses?
Thanks in advance and picture attached. Cheers

 

[StephenStephen]

As an amateur, I'd use decking screws.
Back of an envelope maths at @10 seconds a screw makes it maybe an hour and a half...