So drawing on this idea further.
Circuitry is something like:
WALL -> Trickle chargers -> Battery pack
WALL -> ATX PSUs -> Post Regulated Circuitry (Well call this power source circuitry or PSC)
Battery Pack -> Regulators
PSC -> picoPSU Per motherboard
-> GPU PCI-E connectors
-> 12V to Mobo loom after picoPSU
-> 12V to PCI-E extender
-> Other 12V devices
-> Tiny inverter for supporting 230V devices (ie. if router doesn't accept 12V, 230V Fans.)
Regulator circuitry is: Zener diode + Regulator per "lane", connecting in parallel to 2x1.5F caps.
Now tell me how friggin' dangerous is that setup
No PicoUPS even needed as pack is constantly being charged and 12V being supplied after the regulators. If utilizing PicoUPS then replace the regulator circuitry with them
ATX PSUs then connect to the bank of PicoUPS devices.
Hmmph... Time to build a proof of concept?