320 Amp ONCOR Interconnect

Hello.  I'm new to the forum.  I am installing a mostly DIY 66-panel, 2x FlexBoss, 1x GridBoss system that will have battery backup as soon as I decide which route to take for those.  My questions are AC-side so I'm not certain this forum is proper, but I thought I'd try.

I have a 400A (320A) service with two 200A main panels, both ground-neutral bonded.  I plan to use the GridBoss to take one of the panels and either wire the second panel to pull from the 125A Smart Port on the GridBoss and wire a subpanel for the 3 heat pump heat strips that I don't think the GridBoss and the 3/0 wire can handle, or wire up a 200A transfer switch for the second panel.

ONCOR in North Texas requires a visible disconnect outside to take the solar power completely away from the grid service.  I would like to install two 100A disconnect switches within 10 feet of the meter, one coming from each FlexBoss and running back into the GridBoss from there. 

Question #1: I would like recommendations from anyone with experience backing up a house that occasionally needs more amperage than the 3/0 200A wire going into the GridBoss and how they wired it.  The ideas above (transfer switch or subpanel) are the best I can come up with.

Question #2: Can I have two, properly labeled, disconnect switches to shut down the solar backfeed to grid, or do I need to combine the FlexBoss output into a single 200A disconnect switch, then split it back out to run into the GridBoss?

Hopefully all of that makes sense.

Thank you all for your time.

Greg