Micro-Inverters in the Attic

[ggunn]

Ultimately we plan on working with an inverter manufacturer to make a product optimised for us, but in the mean time we are working with what we've got.

OK, but in operating "out of the box" as much as you are, I think that you are running a significant risk of violating product listings. IMO you should get the microinverter manufacturer to bless whatever you finally come up with before you actually build anything, else you may be painting yourself into a corner.