Great input to chew on from above. Some added points from my new and similar experience:
1. Was told generator should be 1.5 X inverter size, so battery and loads can be managed. I ended up about 1.2, but not worried and I can easily adjust my charger if needed for my passive home backup that's also an auto backup for sump pump.
2. As suggested above, understand exactly what you need. The best thing I ever did was install monitoring system (Sense) that gave me the understanding of what I needed vs wanted. For example, I resolved for home backup no need for 5ton AC or 240v ovens as I live in MI with fully finished 2000 sq ft basement. Other than AC and 240v ovens, I can run HVAC for 5000 home, 3 refrigerators, all the lights, ceiling fans in all rooms etc etc.
3. I went with dual (parallel) inverter generators to manage the THD (<5%). Upgraded my NG meter for increased consumption (potentially). Needed to consider derating of gas inverter generators to about 80% of gas, therefore, 9kw is about 7.2kw for NG. I ended up using Northern Tool open frame product so I could do the conversion myself using Century Fuel kits. This was riskiest part since I gave up my warranties on 2 brand new generators, but felt that wasn't bad as they're still much less cost than name brand (Honda/Generarc) alternative. One pain I had with the product was their "parallel box" wasn't truly a proper 50A plug, so I ended up making my own parallel box. In the end I'm happy to have over 7KW of NG back up power that's less than 100# per unit, so portable and capable, not to mention almost as quiet at the Honda for fraction of $$$$$.
4. To go on further about generator selection, it's really hard to find high KW Inverter Generators, that are NG as well !! Again, I went open frame so I could modify myself. Using 3/4 flex line with dual manifold Quick Connects as a portable solution, that can go with me if I move. Costco sells a Firman trial fuel, but the THD is atrocious! Your Honda is one of the best, but remember with NG 7200 becomes ~ 5.7kw. If you didn't already have the Honda, I'd look at:
The A-iPower GXS7100iRD Dual Fuel With Remote Start Inverter Generator provides 7,100 starting watts and 5,700 running watts on gasoline and 6,400 starting watts and 5,100 running watts on propane.
a-ipower.com
or
In my limited experience, I'd think the top shelf product you already have, the 15K Sol-Ark and the Honda you could manage a definite option, as a start point. Think of as the mandatory prerequisite class "you must" take before taking master level class. New modern inverter may be able to manage exactly what you need, using generator and/or grid power to both charge batteries and handle load(s).
I'd check with who ever helped with the SOK's or SOL-ARK to map up some options and run some numbers.
Lastly, not sure if I missed something, but is this for off-grid, back-up, grid-tied etc ? My case was primarily auto backup (super UPS) for my sump pump, then manual (passive) back up for the whole house (over night without geni's running).
Happy Hunting !