6 inverters and 18 batteries. BMS?

I bought my equipment from Signature Solar (SS).

6 x Growatt 5000 es in parallel
18 x EG4 5.1kwh 48v batteries (92kwh)
96 solar panels with nearly 38kw
All working fine.
I’m 100% off grid. No utility backup. Large 6000 sft home in Idaho.
My system is sized large on purpose to allow charging of my electric vehicle (Hyundai Ioniq 5) and running some other heavy loads even in winter - off grid. I’m not afraid to add more panels or more battery if needed in the future.

Batteries are all Using their own BMS, meaning they’re not connected to the inverters to communicate/be managed by the inverters.
I have 6 batteries to a rack with bus bars. Each of the 3 racks connect to a massive bus bar which is my battery bank terminal. My 6 inverters each connect and draw from this massive terminal bus bar.

Here’s my problem/challenge.
The inverters (paralleled and communicating with each other) can manage only 16 batteries through the inverter BMS. The EG4 batteries only have dip switches for 16. I think that’s part of the limitation.
I have 18 batteries in the bank. So I can’t use the inverter BMS. (SS recommended to let all the batteries manage themselves through their own BMS)
I would prefer to keep my 18 batteries (or expand larger even over time) in my bank.
My inverters don’t know and can’t report battery bank SOC. I’m trying to configure that my generator (Cummins 20kw propane) starts up when battery bank goes down to 15% as a backup option.

What are my options?
(1) stay as is. Let each battery manage itself. Get an external device to fire my generator.
(2) disconnect 2 batteries to get to 16 and let inverter manage bank and generator.
(3) let inverters manage 16 batteries and keep additional 2 batteries in bank, managing themselves with own BMS
(Problematic?)
(4) add some other tool/gizmo to manage my system?
(5) some Other solution I can’t even imagine because I don’t know what I don’t know.

coming in a little late here. these are just my thoughts, I am not an expert by any stretch. I am new to solar as well! but I am hoping that one of the photon sorcerers here might take note of your post and/or correct my thoughts below.

1. I am close to facing the same issue with just 12 batteries. not running out of battery IDs, but if you use Solar Assistant, you must set the first battery ID to 2, which means that you lose the option of battery ID 0 and battery ID 1, so you are limited to 14 batteries.
2. use the capacity you bought, especially as you may be planning on adding more capacity.
3. see #2, but there's not a good solution that I have read about to manage a lot of batteries at once. but the batteries are supposed to be capable of managing themselves. I read a post here one the forum where someone said something equivalent to "I don't see why everyone is obsessed with making the inverters and batteries communicate." shortly afterwards, I ran into issues with just two EG4 inverters playing well with just six batteries, because EG4 has it's own protocol for batteries, and for the host inverter that's connected to the batteries is supposed to be set to 'EG4' battery type, while the slave inverter is supposed to be set to 'user' battery type. while this works, my issue was that on occasion the inverters would swap roles during my setup and things seemed to get funky after that. at that point, I found SolarAssistant, and I have not looked back.
4. I highly recommend Solar Assistant. It can get you data across the entire system. It runs on Raspberry Pi, and I have found it to be very reliable and accurate. what I don't know off hand is if SolarAssistant can handle multiple battery banks across multiple USB to serial connections. I currently have two racks of EG4 batteries, so I can try this out for you and see how SA manages to discover and display data about the two different battery groups that have the same IDs.
5. it's probably worth letting everything manage itself, and just monitor it over a few weeks to see if any anomalies show up. lots of discussion about top balancing the batteries, but I have also read several places here on the forum that it should not be needed on preassembled packs, such as the EG4 rack mount batteries.

Solar assistant works with 4 jbd BMSs each with it own usb to uart
I have 4 batteries and 2 growatts connect to my solar assistant each with own connection to the PI
It is working great. I used a power usb hub to connect more that 4 connects the PI has.

I am a communication advocate. But, not necessary. If you have ample solar, so you reach 100% charge often, then your batteries will be close to balanced most of the time. If not some batteries, that become too low of soc, they will shut themselves off, and miss the next charge cycle. Becoming way out of balance.
Maybe, you would consider splitting the system into 2. I know that makes for some wiring issues, but might be the answer.
And, congratulations on a super system, wow that's big
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