I don't have the Zero with me now but aren't there extra mounting holes in the frame for the side rack? If so a simple strut would make a lot of difference.
Since I've got plans to add a tail later I'm looking to maybe install it in a pelican case like this.
Of course it has to be rotated to no fuck up the streamline too much. But for the rest it seems like a good candidate, it can be mounted very sturdy permanently on the bike, the case it self is also very though and waterproof.
Can somebody shoot holes in this plan or is it decent?
Pelican cases are great. I put an Elcon 2500 in one for a mockup and it seemed extremely sturdy. I still find the rack more of a concern than the case...
Also it will be a bit more forward so it doesn't stick so much out of the back:
Yes, that's a fine idea; push the load forward where it won't act as much like a lever on the top rack.
Putting some basic cushion under it so the seat absorbs some load and oscillation would also be good. For my tail understructure, I'm considering a thick aluminum plate bent into a box shape to fit over my Happy Trails rack and the top rack; and something to distribute the loading onto the seat would help.
Honestly, the new Superchargers / Elcons are short enough that you could just put the case over the seat and use brackets against the side racks themselves, freeing up the top case for normal cargo. I used a Pelican case on an Elcon 2500 vertically in the seat, but I think it'd work better with dual 3.3's and a smaller case:http://electricmotorcycleforum.com/boards/index.php?topic=6480