Hmm. Before anyone else speaks for me, I'll speak for myself:
If I were doing Odyssey over again, one of the very few things I would change would be to eliminate the chassis/start batteries altogether and go with a single bank, just as Bob suggests, with the proviso that the generator has its own separate start battery. The generator, of course, can charge the main bank via a charger once it's started.
My "deep cycle" batteries happen to also carry cranking ratings (Trojan 8D-AGM), which technically makes them hybrid type, but almost all deep cycle batteries have some cranking ability, and if you press hard on the manufacturer they can tell you what the rating is.
Some deep cycle batteries should not be used to crank an engine alone. But in very large banks, an engine starter is just another load. Note that a Trace SW4024 can draw well over 300 amps when operating in surge mode, and that's easily handled by just a single pair of 8D batteries. Typical Delco 24v starter draw is around 800 amps, easily handled by two or three pairs of batteries.
BTW, my Trojan AGMs are rated 1850 CA or 1450 CCA each, so even a single pair can spin the big Detroit without any ill effects, and I would guess that most other 8D size AGM batteries are about the same.
In my case, the house batteries are simply too far away from the starter for me to implement the single-bank system now. (The location was chosen for weight and balance reasons.) So I continue to use separate starting batteries (a pair of Group 65s) for cranking purposes, and the two banks get bridged 30 seconds after the alternator comes on line.