SPD Sanity Check - L1, L2, N Protection Multiple Locations

[artuza]

I have been pouring over various forums for the last couple of years (including here) regarding SPD's (reviews, real world experience, usage / configurations) and have narrowed it down to using MNSPD300AC's vs. some of the other available products.

Per the old NEC rules regarding the use of grounds utilized by my AHJ nearly 20 years ago, all four locations (utility pole, main home, barn, shop) have individual grounds bonded at each location.  There is no 4th ground wire between the four locations, nor are there any other metallic utilities between the four locations (telecom, ethernet, coax, water, gas).  My network / IP Phone connections are fiber optic.

Since I am looking at protecting all three lines (L1, L2, N) at all four locations, I see each panel location would require 2 SPD's each.

For locations at the utility pole panel, barn, shop, home panel:  SPD-1 attaches to L1 and L2, SPD-2 attaches to Neutral.  This will leave one leg on SPD-2 unconnected.  Is this safe, or should the second leg be attached to Neutral as well? 

There is a fifth location - the Transfer Switch outside the home panel and next to the generator (Generac 26K) requiring 3 SPD's:  SPD-1 connected to utility L1 and L2; SPD-2 connected to generator L1 and L2, SPD-3 connected to utility Neutral and generator Neutral.  I presume the use of SPD-3 to capture both utility and generator neutrals is permissible (each leg is isolated internally which dumps to the same common ground)?

Any useful inputs and answers to my two questions would be greatly appreciated.

Thank you in advance.
Alex Tuza