As long as the dump load is big enough to deal with ALL the incoming power, then I do not believe there is a whole lot of concern in a system like this.
As far as gassing should not be an issue because the gassing is based (mostly) on the overvoltage and charge rate.
If the battery is Not overvoltage, and the dump load is big enought, I don't belive short term C/1 charging is very bad.
That is with a controller circuit that is fast enough to deal with everything, meaning NO Relay based "Controllers".
I did some silly (meaning very abusive) stuff to 7AH SLAs when prototyping the ghurd controller.
Charging amps at maybe 1.3C (C/0.75), or more. Dump loads at 2C (C/0.5), or more.
It would be more silly to undersize a battery bank that much in a real, working, system.
Disclaimer: "As far as I could tell", nothing became warm, the battery was happy, no issues, etc.
Again, that is with a fast controller (NO Relays). It was to test the circuit(s) and not the battery.
I still use that battery.
G-