Take the S-hook of a bungee strap and push it into the lock area of the hatch, the lock will lock around the S-hook and never let go, well until you push the UNLOCK button and pull on the S-hook.
'16 boards might be an issue I believe it's not much more than 9' from the dash to hatch lip, that would mean the boards would hang out 7'.....for sure you'd need a red flag attached to the end of the boards, I think it might stick out a bit too far out without support.....
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a